Mark Zuckerberg was about to spend up to $200 billion, more than the entire Disney company is worth, on an AI that didn't exist yet. So he asked the guy building it if he was sure it would work, and even that guy wasn't sure. The guy is Alexandr Wang, who runs Meta's AI lab, and the story came out on John Collison's podcast this week. Late last year Meta's top executives were together in Hawaii, and Wang says the CFO, Susan Li, pulled him aside more than once on that trip to warn him that if…