I'd deny even that. He made enough dumb decisions that he was forced out and got rich primarily because of other peoples' good ideas/decisions.
This is an entirely mutually voluntary arrangement.
If the company does not deliver on its contractual obligations to you, you can take them to court, and you'll win.
If you don't get more than you accepted in the contract, you have no cause to claim being "screwed over".
If you don't read the contract before you sign it, that's on you.
P.S. I've added adendums to employment contracts listing the separate intellectual property that was mine and would remain mine. I never got any pushback on that. Also, I've started side projects while employed, and before working on them, I'd get a signoff from an executive that it was not covered by my employment contract. And I never got "screwed over".
But if you come from “so much money we couldn't even close our safe” as his father put (quote from Wikipedia
Then you do have a leg up