Go big or go home. That’s the motto of one mysterious investor who put his chips on the table, buying close to $400 million of the No.1 digital currency, bitcoin. The purchase comes as cryptocurrencies are making a comeback after a dreadful start to 2018. Major digital currencies lost as much as 50% to start the year as growing regulation and security fears crippled the market, seeing traders bail on their positions. However, the tide has turned. The price of bitcoin BTCUSD, +1.61% has increased more than 60% since trading under $6,000 on February 6, pushing back above $10,000, helped by signs of growing recognition of digital currencies from officials in Washington. “Not sure who that big buyer..."