Sure, we all agree.
The solution is pretty obvious, just implement a wealth tax that prevents capital flight.
It’s not that hard. The US already taxes its citizens abroad. A well-implemented wealth tax would be charged regardless of where you live or where your money is. If you are a US citizen you get taxed. Then you slap an exit tax on citizenship revocation and you’re good to go.
Not hard, simple, we already have systems in place to enforce it.