That's not how the real world works.
People see a huge tax bill here and a much lower tax bill there and they move, at least for tax purposes.
Brits moved to France in the 70s. French move to Belgium and the UK now.
We all do this within our means.
Yes we should all pay our fair share of tax to finance public services but we work to make money for ourselves, not the state, hence why I think important and highly symbolic that the marginal income tax rate stays below 50%. Beyond that you're working for the state not yourself.
There's a term here in the UK: Champagne socialist.
But all that is besides the point really.
It is preferable to have successful people who move towards things. People trying to move away from things are useless regardless how much money they have. They are beyond useless! Who needs them with there unambitious greed? What good will come from them? As you describe, all they care about is themselves? Their money will do nothing but build the next rent seeking scheme simply to take it away.
We should really buy them a large cruise ship and give them a going away party. Ill be standing there waving until she vanishes over the horizon. Then ill softly whisper: Goodbye angry men, may you find greener pastures elsewhere.
You cant have to much socialism and you cant have to much oligarchy. Or put differently: you cant have to much empathy and you cant have to much psychopathy.
If the balance is distorted (not saying it is) it will have to be corrected or you get a destructive runaway effect.
These people are of the opinion that the rich can afford to pay more tax and that the money can be used for under financed systems already in place. If that is the goal (not saying it should be) making a few millionaires run away would be beneficial. They would take with them a substantial amount of greed.