Don't most billionaires have at least some of their assets in the American financial ecosystem? If so then one could find buyers via extortion: first sanction them or freeze their assets, then make permanent residents and citizens exempt from sanctions.

Aha, you are right. This has always been the way he does business.

this assumes that trump's government would chase these billionaires to shake them down, and shake them down on behalf of the government.

instead pay a one-time fee to the man himself and do whatever you want.