AUSTIN — On a Friday morning last spring, Mark Suman called out sick from his job as a senior engineering project manager at Apple and made his way downtown to a place called the Bitcoin Commons, a sort of clubhouse for enthusiasts of the world's largest cryptocurrency, situated a few blocks south of the Texas State Capitol.At the time, Suman was, in his words, "an active hobbyist," tinkering with the technology in his spare time. "I actually played around with it a bit within Apple as well," he...