Meta's Open Source AI Mistake

With all the talk of $100M signing bonuses or offers or both or whatever, we're looking right past the issue of "why". That is, why does Mark Zuckerberg have to offer such incredible amounts of money to convince people to come over to work on Meta's new "Superintelligence" team? You keep hearing that it's the market and it's crazy right now. But that's mainly true because it's Meta who are the ones setting this market!
Again, why?
The high level answer is obvious: they need to play catch up. But for months and months seemingly all we've heard out of Meta is how much their products are "killing it" and they're the leaders in AI. Obviously, that wasn't true. But again, why? Seemingly part of it was a fundamental bet which Zuckerberg made that may have backfired. That is, the bet on open source.