Thats a big stretch and a huge thought experiment, and way out of scope of what we're talking about (but no I don't). Any sort of systemic change on that scale would make me reevaluate where I live though - if for example I lived on a country that flip flopped between right wing and centrist every four years I would be pretty uncomfortable with that.

> Suppose it was easy for all of those high performers

A bit of a nitpick, but an important one. High performers and high earners are not the same thing.

You don't need to suppose. It already happened recently in France.

When the Socialist government increased the marginal tax rate to 70% for millionaires, there was a huge capital flight and they lost revenue.

No there was not a huge capital flight. This have been aborted solely because of threats from the ultra richs in France.

Moreover, this law was actually pretty fair : it was applied on marginal annual revenue over 1M so it meant that you had to be actually a multi-millionaire to be concerned.

No, France didn't threaten to force high earners to leave, they tried to enforce a higher tax on the absolute absolute highest earners in the country. Even making 3-400k you would have been unlikely to have been affected by this. Funnily enough, you'll also notice the bluster was about people leaving to other EU states and not to the US.

Also, to call the French government socialist I'd completely laughable. Maybe in comparison to somewhere like Hungary, sure.

I am not talking about Macron, I am talking about Hollande, which is (was?) the leader of the Socialist Party.

And I may be wrong about it, but I think that he increased taxes all across high-income brackets, not just the absolute top. And that certainly leads to a game-theoretical equilibrium.

To me (and I assume others) the following calculation comes into play:

- for what I pay in taxes, do I get a reasonably good public services back? I am not saying that I want to account for every euro, but I don't want to feel like I did in Brazil, paying 38% effective tax rate and receiving virtually nothing back in public services and still having to pay again for private healthcare, private education for the kids, etc...

- how much money do I have left in the bank after I paid all my expenses and taxes, i.e, what is my saving power?

If I had a 250k€/year brutto income, it wouldn't be too difficult to show that I would be better off in Switzerland (higher CoL, but way lower tax rate) or in Greece (similar tax rates, less return on public services, but way lower CoL). If Germany decided to increase the effective tax rate, this threshold would go down significantly.