The problem I see is that rich old man has a lot of cash, and governments compete globally for that mans investment dollars. If you tax him theres some euclidean point where it no longer makes sense to invest.
If you're talking about taxing a person making 1 million dollars 75% and taking away 750k is that really fair? If you're some kind of genius programmer or CEO who went to Harvard would you stay for 25%?
We need to remove the tax loophole that people like Elon Musk use, where they borrow money to avoid paying taxes.