Why do people keep working and earning more when they are set for life--what actual practical purpose does megawealth serve once you've guaranteed your standard of living for you and your offspring? The purpose is lack of accountability. Megawealth means you can spend every remaining day of your life screwing up, and besides doing something illegal that lands you in jail, you'll never suffer a consequence.
I think this is the wrong question to ask -- "what end is this a means to anymore". One of the largest challenges in life is pursuit of meaning, and Zuck has, at least he thinks, found it. He still has consequences, but they are higher up on Maslow's hierarchy of needs.
You could argue that those in charge should have enough at stake to feel the burn of a layoff like this, but this issue isn't dissimilar to biology. We often make local (and temporary) sacrifices on behalf our own bodies, knowing "we" will still be around afterwards to enjoy life and the removed parts won't (removing limbs, wiping out blood cells, organ removal, etc.). This isn't 1:1 with Zuck, because Zuck is more than just his role in Meta, but close enough.
Actually, yes, as it could open up career opportunities for others further down the totem pole. At almost every company I've ever worked, the CxO, SVP, VP roles were all hogged up by already-set-for-life people (or people who became set for life by working there a few years). They just hang on to those very senior roles like barnacles, while the rank and file fight each other their whole careers for a few open Director or manager roles.
If already-rich people could just admit they won the game and gracefully resign to "spend more time with their family" or "look down their noses" or whatever rich people like to do, maybe some of those Directors could be promoted to VPs and some of those managers could be promoted to Director and so on. This would help refresh the tree a little, cycle new blood through leadership, and help even more people climb the ladder.
Is that ritual suicide?
If they just give it to you straight, there’s no bullshit - the people fired may be mad or upset but they'll be mad or upset regardless because being fired sucks. If they start hand-wringing, talking about how painful it was for them and how they take full responsibility people will ask “hang on, how exactly is this painful for you? how are you taking responsibility, what are you doing about it?”