NEW YORK (MarketWatch) -- Bitcoin is "not a currency" because it doesn't meet the criteria of a currency, including being a store of value, said Berkshire Hathaway BRK.A, +0.36% [s:BRKB] Chairman and CEO Warren Buffett. In an interview on CNBC Monday, the American business magnate said that he would not be surprised if bitcoin is not around in 10 or 20 years because it is used as a speculative bet. The price of bitcoin is inevitably based on the value of the dollar he said, which means that it is not a currency in and of itself.