This past February, just as Bitcoin was shedding more than half its value, Aaron Fernstrom watched a glistening red Mercedes E-class sedan pull into a parking space at the Albemarle rental complex where he was living temporarily. The vanity license plate hinted at the source of funds: “BITCOIN.” “I just shook my head and thought to myself, ‘There goes another one’ — another person who made a quick fortune trading tulips,” Fernstrom, a former venture capitalist, said from his office at the Darden School of Business at the University of Virginia. “There are always those few people who, by pure l...