It’s 7 p.m. on a Thursday, and I’m drinking a beer next to a Bitcoin ATM. On the wall in front of me is an illustration of a masked Satoshi Nakamoto: “Don’t Delay—Be Your Own Bank,” it announces. It’s one of several portraits of Satoshi, including one that features him taking off from a dollar bill as if he were a superhero. (The portraits are particularly creative, since no one knows who Satoshi—a pseudonym—really is.) A TV is mounted above the bar, displaying the current values of hundreds of cryptocurrencies: Bitcoin occupies the biggest space on the screen, followed by...