They can (and many probably do) put a small amount of their income into conservative boring low yield investments and still be set for Life if everything else collapses. Maybe not with the yacht, prestige or power they hoped for but still more comfortable than most of the population.

The best a CEO can do is take responsibility by making a significant financial sacrifice and not bullshit their former employees on the way out. I think this letter does it as best as possible given the circumstances but it can't bridge the gap between them and most people.

CEOs chose to be in that position and I'm sure they can handle a little criticism from the internet