They built the wealth on the back of their nation, on the back of the infrastructure, education, laws and blood of their ancestors, no good reason they should keep it when they choose to leave.
It's the fundamental basis behind tax. 95% tax on any wealth over, say, $500k on renouncing citizenship, total forfeit if found to be hiding assets, done.
If you have to come up with ways to stop people from fleeing your country instead of too many people wanting to enter your country then you probably have a problem. And no, I don't think it is as easy as you say. Simple sounding solutions like this can have huge disastrous consequences.
My socialist country didn't even allow people to travel - to prevent capital flight and brain drain - and now you are proposing to basically close borders to some people until you buy your own freedom.
That's scary as hell and a return back to 1920s.
America is one of the only countries to tax their citizens income abroad.
This would affect 0.001% of people who had managed to capture a huge amount of wealth and were attempting to avoid taxes.
Indeed, wealth tax sounds good because there are problems with income inequality and it's currently fashionable to hate the rich. But that's about where it ends, while second-order effects are ignored or at least not taken seriously.
Andrew Yang was one of the few high-profile Democrats brave enough to push back on it.
"I think the wealth tax is an idea, in spirit, that makes sense, given the wealth distribution. But in practice it would have massive implementation problems. There would be capital flight, wealthy people would renounce their citizenship. And the bigger problem isn’t even the money. It’s the annual inventorying of their assets. The truly wealthy in this country have zero interest in submitting to an annual audit of all of their assets. They barely know what all their assets are. And the last thing they’re going to do is report them every year and then pay a toll. So you would have massive compliance problems. And to me there are better ways to make this economy fair, though I understand the spirit of it and the intent of it. But I agree that it would be somewhere between problematic and a disaster in practice."
https://www.cnbc.com/2019/10/02/andrew-yang-wealth-tax-plans...