alt Hacker NewsShort term: no
Long term: yes, especially if you combine really high taxes in the 40+% range with consistently rubbish public services
But the real question is not whether people will leave, the question is how many talented hard working people chose not to move to your country in the first place because your taxes were too high. It won't show up in any data, you'll just experience worse economic growth and have to tax everyone else more
The answer is just no. Massachusetts passed a tax on income over a million dollars and despite the ads that were obvious lies, we have more millionaires now than we did a few years ago. Turns out, rich people like to live in places that have well funded infrastructure, good schools, a thriving art scene, etc...