This is definitely what America is going for and definitely not the way things are right now. It’s very much possible to leave and or or move money legally.
I agree once you’ve built up a bank account as a us citizen it’s quite hard to. But if you saw this coming, you could easily have an XYZ USA, an XYZ China, etc.
If you own a holding company in another country, you need to declare that and be taxed on it in addition to that country's tax.
I know this because I own a business and wish to live abroad so I really would like to leave but I can't.