On 25 March 2014, the United States Internal Revenue Service (IRS) ruled that bitcoin will be treated as property for tax purposes. This means bitcoin will be subject to capital gains tax. In a paper published by researchers from Oxford and Warwick, it was shown that bitcoin has some characteristics more like the precious metals market than traditional currencies, hence in agreement with the IRS decision even if based on different reasons.
Ethereum was initially described in a white paper by Vitalik Buterin, a programmer involved with Bitcoin Magazine, in late 2013 with a goal of building decentralized applications. Buterin had argued that Bitcoin needed a scripting language for application development. Failing to gain agreement, he proposed development of a new platform with a more general scripting language.:88
The U.S. federal investigation was prompted by concerns of possible manipulation during futures settlement dates. The final settlement price of CME bitcoin futures is determined by prices on four exchanges, Bitstamp, Coinbase, itBit and Kraken. Following the first delivery date in January 2018, the CME requested extensive detailed trading information but several of the exchanges refused to provide it and later provided only limited data. The Commodity Futures Trading Commission then subpoenaed the data from the exchanges.
Bitcoin, along with other cryptocurrencies, has been described as an economic bubble by at least eight Nobel Memorial Prize in Economic Sciences laureates, including Robert Shiller, Joseph Stiglitz, and Richard Thaler. Noted Keynesian economist Paul Krugman has described bitcoin as "a bubble wrapped in techno-mysticism inside a cocoon of libertarian ideology", professor Nouriel Roubini of New York University has called bitcoin the "mother of all bubbles", and University of Chicago economist James Heckman has compared it to the 17th-century tulip mania. Former Federal Reserve Chairman Alan Greenspan has also described bitcoin as a "bubble"; the investors Warren Buffett and George Soros have respectively characterized it as a "mirage" and a "bubble"; while the business executives Jack Ma and Jamie Dimon have called it a "bubble" and a "fraud", respectively.
Bitcoin has been criticized for its use in illegal transactions, its high electricity consumption, price volatility, and thefts from exchanges. Some noted economists, including several Nobel laureates, have characterized it as a speculative bubble. Bitcoin has also been used as an investment, although several regulatory agencies have issued investor alerts about bitcoin.