Fair, and I don't believe we'd be better off if they fled. We would be better off if they weren't astronomically wealthy. I don't have a specific number in mind, but "a billion-ish" feels like a reasonable upper bound on wealth.

I'd also note that I would prefer to adjust tax/accounting laws to prevent the accumulation in the first place, not just roll out a blanket "take everything over a billion-ish law" as that feels more like a band-aid than a fix.