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Economics of bitcoin
Bitcoin is a digital asset designed by its inventor, Satoshi Nakamoto, to work as a currency.
Classification
Bitcoin is a digital asset designed by its inventor, Satoshi Nakamoto, to work as a currency. It is commonly referred to with terms like: digital currency,:1 digital cash, virtual currency, electronic currency, digital gold, or cryptocurrency.

The question whether bitcoin is a currency or not is disputed. Bitcoins have three useful qualities in a currency, according to The Economist in January 2015: they are "hard to earn, limited in supply and easy to verify". Economists define money as a store of value, a medium of exchange and a unit of account, and agree that bitcoin has some way to go to meet all these criteria. It does best as a medium of exchange: As of March 2014, the bitcoin market suffered from volatility, limiting the ability of bitcoin to act as a stable store of value, and retailers accepting bitcoin use other currencies as their principal unit of account.

Classification of bitcoin by the United States government is to date unclear with multiple conflicting rulings. In 2013 Judge Amos L. Mazzant III of the United States District Court for the Eastern District of Texas stated that "Bitcoin is a currency or form of money". In July 2016, Judge Teresa Mary Pooler of Eleventh Judicial Circuit Court of Florida cleared Michell Espinoza in State of Florida v. Espinoza in money-laundering charges he faced involving his use of bitcoin. Judge Pooler stated "Bitcoin may have some attributes in common with what we commonly refer to as money, but differ in many important aspects, they are certainly not tangible wealth and cannot be hidden under a mattress like cash and gold bars." In September 2016, a ruling by Judge Alison J. Nathan of United States District Court for the Southern District of New York contradicted the Florida Espinoza ruling stating "Bitcoins are funds within the plain meaning of that term.— Bitcoins can be accepted as a payment for goods and services or bought directly from an exchange with a bank account. They therefore function as pecuniary resources and are used as a medium of exchange and a means of payment." The U.S. Treasury categorizes bitcoin as a decentralized virtual currency. The Commodity Futures Trading Commission classifies bitcoin as a commodity, and the Internal Revenue Service classifies it as an asset.

The South African Revenue Service, the legislation of Canada, the Ministry of Finance of the Czech Republic and several others classify bitcoin as an intangible asset.

The Bundesbank says that bitcoin is not a virtual currency or digital money. It recommends using the term "crypto token."

The People's Bank of China has stated that bitcoin "is fundamentally not a currency but an investment target".

Journalists and academics also debate what to call bitcoin. Some media outlets do make a distinction between "real" money and bitcoins, while others call bitcoin real money. The Wall Street Journal declared it a commodity in December 2013. A Forbes journalist referred to it as digital collectible. Two University of Amsterdam computer scientists proposed the term "money-like informational commodity". In a 2016 Forbes article, bitcoin was characterized as a member of a new asset class.

In addition to the above, bitcoin is also characterized as a payment system.:1

General use
According to research produced by Cambridge University in 2017, there are between 2.9 million and 5.8 million unique users actively using a cryptocurrency wallet, most of them using bitcoin. The number of active users has grown significantly since 2013 (there were 0.3 to 1.3 million unique users at the time).

Buying and selling
Bitcoins can be bought and sold both on- and offline. Participants in online exchanges offer bitcoin buy and sell bids. Using an online exchange to obtain bitcoins entails some risk, and, according to a study published in April 2013, 45% of exchanges fail and take client bitcoins with them. Exchanges have since implemented measures to provide proof of reserves in an effort to convey transparency to users. Offline, bitcoins may be purchased directly from an individual or at a bitcoin ATM. Bitcoin machines are not however traditional ATMs. Bitcoin kiosks are machines connected to the Internet, allowing the insertion of cash in exchange for bitcoins. Bitcoin kiosks do not connect to a bank and may also charge transaction fees as high as 7% and exchange rates US$50 over rates from elsewhere.

As of 2016 it was estimated there were over 800 bitcoin ATMs operating globally, the majority (500+) being in the United States.

Price and volatility
According to Mark T. Williams, as of 2014, bitcoin has volatility seven times greater than gold, eight times greater than the S%story%P 500, and 18 times greater than the U.S. dollar.

Attempting to explain the high volatility, a group of Japanese scholars stated that there is no stabilization mechanism. The Bitcoin Foundation contends that high volatility is due to insufficient liquidity, while a Forbes journalist claims that it is related to the uncertainty of its long-term value, and the high volatility of a startup currency makes sense, "because people are still experimenting with the currency to figure out how useful it is."

There are uses where volatility does not matter, such as online gambling, tipping, and international remittances. As of 2014, pro-bitcoin venture capitalists argued that the greatly increased trading volume that planned high-frequency trading exchanges would generate is needed to decrease price volatility.

The price of bitcoins has gone through various cycles of appreciation and depreciation referred to by some as bubbles and busts. In 2011, the value of one bitcoin rapidly rose from about US$0.30 to US$32 before returning to US$2. In the latter half of 2012 and during the 2012–13 Cypriot financial crisis, the bitcoin price began to rise, reaching a high of US$266 on 10 April 2013, before crashing to around US$50. On 29 November 2013, the cost of one bitcoin rose to the all-time peak of US$1,242. Some evidence suggests that part of this peak in the price of bitcoin was due to price manipulation. In 2014, the price fell sharply, and as of April remained depressed at little more than half 2013 prices. As of August 2014 it was under US$600.

In January 2015, noting that the bitcoin price had dropped to its lowest level since spring 2013 – around US$224 – The New York Times suggested that "ith no signs of a rally in the offing, the industry is bracing for the effects of a prolonged decline in prices. In particular, bitcoin mining companies, which are essential to the currency's underlying technology, are flashing warning signs." Also in January 2015, Business Insider reported that deep web drug dealers were "freaking out" as they lost profits through being unable to convert bitcoin revenue to cash quickly enough as the price declined – and that there was a danger that dealers selling reserves to stay in business might force the bitcoin price down further.

Economic theory suggests that the volatility of the price of bitcoin will drop when business and consumer usage of bitcoin increases. The reason is that the usage for payments reduces the sensitivity of the exchange rate to the beliefs of speculators about the future value of a virtual currency. According to The Wall Street Journal, as of April 2016, bitcoin is starting to look slightly more stable than gold. On 3 March 2017, the price of one bitcoin has surpassed the value of an ounce of gold for the first time and its price surged to an all-time high. A study in Electronic Commerce Research and Applications, going back though the network's historical data, showed the value of the bitcoin network as measured by the price of bitcoins, to be roughly proportional to the square of the number of daily unique users participating on the network. This is a form of Metcalfe's law and suggests that the network was demonstrating network effects proportional to its level of user adoption.

As a speculative bubble
Further information: Cryptocurrency bubble
Bitcoin has been characterized as a speculative bubble by eight laureates of the Nobel Memorial Prize in Economic Sciences: Paul Krugman, Robert J. Shiller, Joseph Stiglitz, Richard Thaler, James Heckman, Thomas Sargent, Angus Deaton, and Oliver Hart; and by central bank officials including Alan Greenspan, Ben Bernanke, Janet Yellen, Agustín Carstens, Vítor Constâncio, and Nout Wellink.

The investors Warren Buffett and George Soros have respectively characterized it as a "mirage" and a "bubble"; while the business executive Jack Ma has called it a "bubble".

Views of economists
In 2014, Nobel laureate Robert J. Shiller stated that bitcoin "exhibited many of the characteristics of a speculative bubble"; in 2017, Shiller wrote that bitcoin was the best current example of a speculative bubble.

Economist John Quiggin in 2013 said "bitcoins are the most demonstrably valueless financial asset ever created".

Researchers Neil Gandal, JT Hamrick, Tyler Moore, and Tali Oberman claimed that in late 2013, price manipulation by one person likely caused a price spike from US$150 to more than US$1000.

Nobel laureate Joseph Stiglitz in 2017 said "It’s a bubble that’s going to give a lot of people a lot of exciting times as it rides up and then goes down." He emphasized its use by criminals, its lack of a socially useful purpose, and said that it should be outlawed.

Nobel laureate Paul Krugman wrote in 2018 that bitcoin is "a bubble wrapped in techno-mysticism inside a cocoon of libertarian ideology". He criticized it as a very slow and expensive means of payment, used mostly to buy blackmarket goods, without a "tether to reality".

Nobel laureate Richard Thaler emphasizes the irrationality in the bitcoin market that has led to the bubble, demonstrating the irrationality with the example of firms that have added the word blockchain to their names which have then had large increases in their stock price. The extremely high volatility in bitcoin's price also is due to irrationality according to Thaler.

Four Nobel laureates, James Heckman, Thomas Sargent, Angus Deaton, and Oliver Hart, characterized bitcoin as a bubble at a joint press conference in 2018. Hart cited Christopher Sims's work showing no intrinsic value to bitcoin. Heckman compared bitcoin to the tulip bubble. Deaton pointed to bitcoin's use by criminals.

Professor Nouriel Roubini of New York University has called bitcoin the "mother of all bubbles", writing that the underlying blockchain technology has "massive obstacles standing in its way", including a lack of "common and universal protocols" of the kind that enabled the early Internet. According to Roubini, bitcoin has failed as a unit of account, a means of payment, and as a store of value; he calls the claim that bitcoin cannot be debased "fraudulent". "Scammers, swindlers, charlatans, and carnival barkers (all conflicted insiders) have tapped into clueless retail investors' FOMO ('fear of missing out'), and taken them for a ride," he writes.

Views of central bank officials
Early claims that bitcoin was a bubble focused on the lack of any intrinsic value of bitcoin. These claims include that of former Federal Reserve Chairman Alan Greenspan in 2013. He stated "You really have to stretch your imagination to infer what the intrinsic value of Bitcoin is. I haven't been able to do it."

In 2017 Greenspan compared bitcoin to the Continental dollar, which ultimately collapsed. He said "Humans buy all sorts of things that aren't worth anything. People gamble in casinos when the odds are against them. It has never stopped anybody."

Former Fed Chair Ben Bernanke (in 2015) and outgoing Fed Chair Janet Yellen (in 2017) have both expressed concerns about the stability of bitcoin's price and its lack of use as a medium of transactions.

Agustín Carstens, head of the Bank of International Settlements, has called bitcoin "a combination of a bubble, a Ponzi scheme and an environmental disaster", and warned of cryptocurrencies undermining public trust in the financial system.

David Andolfatto, a vice president at the Federal Reserve Bank of St. Louis, stated, "Is bitcoin a bubble? Yes, if bubble is defined as a liquidity premium." According to Andolfatto, the price of bitcoin "consists purely of a bubble".:21

Comparisons of bitcoin to the tulip mania of seven*****th-century Holland have been made by the vice-president of the European Central Bank, Vítor Constâncio and by former president of the Dutch Central Bank, Nout Wellink. In 2013, Wellink remarked, "This is worse than the tulip mania At least then you got a tulip [at the end], now you get nothing."