I started with the idea that I'd question whether the guy got his money by doing more harm than good, USD being issued based on whether a loan is expected to be profitable, not whether it benefits the people who are expected to accept it. Maybe it's in your best interest to not blindly support whatever the loan was for by accepting his money. Maybe it was for mining that's poisoning your drinking water. That failure to align incentives (i.e. implicit global fungibility) is the specific deficiency that I see killing USD and it's equivalents.
But specifics aren't necessary for the broader argument: Power corrupts, and enough corruption ends the tenure of the powerful. The details of how that is playing out for USD aren't especially relevant.
Your example was clumsy because you have to construct elaborate weird scenarios that don't ever happen for crypto to make sense. Guys have to come up to you in the street and buy your shoes. Entire economies and payment systems have to be assumed to have collapsed. It is a fantasy.
Can I do that with crypto currency? Not so much, really.