It's always been a fallacy that the rich can remove their money from all developed economies and still remain rich. Also, if billionaires are taxed until they're no longer billionaires, that money hasn't disappeared, it's been recycled.

And there's a fundamental series of questions under all this: who elected billionaires? Who benefits from their continuing to be billionaires? What are the costs? How can we fire them?

The ancient Athenians would vote to expropriate and exile the rich if they weren't working in the interests of the polis (cutting deals with enemy states, interfering in politics, corruption). Perhaps Western countries should all pass laws that a limited number of referenda can be held annually to make a similar disposition of the modern ultra-rich?