I doubt he would have turned to fraud or become a proxy if he had $50M of his own.

Your theory is the US just snatched some multi-millionaire off the street and got them to confess to some crimes they didn't commit?

Here in the US if you have that much money you can get away with crimes you did commit.

A foreign multimillionaire. Those are worth less, especially if their state owes the US some favors (or doesn't like him in the first place).

That said, sure, having $50M to return points to him being complicit -if not the mastermind- on this. Especially since I don't think we're explicitly told he was multimillionaire to begin with, just a businessman, which can even mean a guy that sells lemonade at a street corner (as long as he owns the stand).

But, and this is what I wanted to point out, returning $50M, doesn't make it entirely implausible.

This boils down to the question: can a multimillionaire ever be successfully framed for something?

I say, why not?

I'd say there's a good chance he was a proxy who had full control of many/all the bank accounts involved, but also had little knowledge that they existed or were set up in his name.

Hmm, that's another possibility, yes! Him having control (as the accounts were made in his name) but no prior knowledge of them or what they'd be used for.

(Though this begs the question how come the real con hadn't gotten the money by then, perhaps they did it piecemeal e.g. to not draw attention, which might explain why only $50M were left).