Best I can tell (I would never have to worry about such a thing) the current exit tax rate is about 24%. Significant to be sure but well below the 100% you seem to think would happen if someone renounces their citizenship and changes domiciles.

Confiscating everything one owns for use by the government isn't something that aligns with US DNA. Remember, the Revolutionary War emerged from conflict with Great Britain over taxation. Also, what represents "fair" taxation is not an absolute. Everyone's definition of "fair" is different.

Currently, 50% of the population in the U.S. pay 3% of total income taxes while 1% of the population pay about 38%. Thus, we already have, by definition, a progressive tax system. It may not be as progressive as some would like but it is nonetheless, progressive.

Sure, if Jeff Bezos leaves, the US would get about 50 Billion of his 200. But he'd take the rest somewhere else and put it to work. Does that really make sense in the long run.

We need a different approach to rebalancing income and wealth inequality. One that is based more on capturing the ever increasing productive capacity of technology and automation before it reaches the bank accounts of the 1%. Clawing it back after the fact invites them to go elsewhere.