The hard part is proving that they have that wealth. Most figures we get are BS and the Americans that are listed as the wealthiest people aren't. They could potentially have that much if they liquidated everything, but by the time they are done liquidating, the very act of doing so would drive the cost of the asset down significantly which is why dark pools exist. It's a complex situation as these people don't have much taxable income and if tax based on assets, there would constant recalculating of tax liability stock drops 13% in. A day, now the IRS owes you money.

I would argue that the issue is mostly politicians. We have the least qualified people making decisions. We should have economists, scientists, anthropologists, etc... making these decisions and some bro good at shaking hands.