Brian Armstrong says Coinbase started an internal venture bets program so great ideas—and great people—don’t walk out the door: “We have something internally called Next Bets. Twice a year, we have a panel where anybody in the company can come in and pitch and say, ‘I think we should be building this.’” “My fear was from reading things about Steve Wozniak at Hewlett-Packard. He famously went to HP and said, ‘I think we should build a personal computer.’ They said no, and he left to found…