Yeah, the wealthy “giving it all away” is always a bullshit scheme in some way. If they really felt that way, they would have shared the profits with those who helped create them. This sort of wealth only happens in literally one situation: greed overcomes compassion for others.
These schemes usually fall into one of three categories:
I fucking hate my kids and don’t have anyone I think actually deserves this money, so I’m giving it to some random charities of my choosing when I die because I know damn well I can’t spend it all and I have to do something with it
I’m just putting it all into a charitable trust that I still have full control over and likely won’t spend much out of it, unless it benefits me personally
Straight up bullshit PR campaign about a future promise that is not binding
Quite often, it’s a combination of 1 and 2, locking up the money for a loooong time and only to be used for a specific purpose.