It's often about preservation of wealth more than gains for these people.
That said I've discussed some returns they make and it's incredible. I don't want to say what I recall, as it was a couple years back and it sounds like an exaggeration. They said this is partly because they get access to deals that don't hit the wider market and you need serious cash to get in the room to have that chat. And I guess these manager have a bunch of the right people attached to them so it makes an easy stop.