Companies are made of individuals whose interest isn't necessarily aligned with that of its shareholders. For example, Google and Microsoft are run by executives who only own a tiny percentage of their respective company's stock, so they have little to lose by gambling their company's money on over hiring. If these new hires are useful, they get even bigger bonuses, but if they don't they won't be punished too harshly because basically every other executive made the same "mistake".

On the other hand, Zuckerberg would rather create the metaverse rather than cash out on Facebook, so he decided to throw unlimited money at it until he received severe pressure from shareholders.