Where are they going to go? And once you come to the logical conclusion that only a few outliers will actually "leave", they will leave a void that someone will fill, and be taxed.
I'm not sure about American prefences but in Europe people tend to use Switzerland, Monaco and Malta.
In Asia, you have Hong Kong and Singapore, both relatively safe and decent countries. Maybe Macau, but I'm not sure.
You're also assuming the government can just "implement" the "ideas" you have and everything will be alright. As if they really rich will give in without resistance. It doesn't work with drugs, it won't work with money.
You add laws, they find loop holes, and I'm pretty sure the private sector can afford smarter people than the government. The government will be too slow and inefficient to tackle this, unless you turn into Germany BOM ;-).
So now you're spending resources to gain resources, which... might stimulate the economy, sure, heh gotta spend money to make money, aye?
Jokes aside, to make things easier, imagine the war on drugs. It doesn't work no matter how much you yell drugs are bad. You can tell "tax" the rich, but as an idea it doesn't mean shit, unless you manage to implement it, which I have my doubts.
The best solutions are always the most pragmatic ones, it can be hard to see it when ones views are clouded with personal feelings. I can admit I that there are some things I wouldn't want to compromise on.. again, Germany.
I'm also suspecting you're assuming leave as in physically leaving, you're in for a surprise when you find out that the truly rich can have the cake and eat it so no one would "fill" their void if there are options, and there will always be options for someone who is truly rich.
Otherwise you just end up taxing the shit out of regular employees, some who makes higher salaries in volatile markets.
Your conclusion isn't logical. Human nature, machines, etc etc.
Where are they going to go? And once you come to the logical conclusion that only a few outliers will actually "leave", they will leave a void that someone will fill, and be taxed.