Just look at Panama this very week. They were threatened to be invaded if they didn't give up economic deals with China and go back to being a servant colony of the US.

The odds of citizens cashing in and demanding all their money at once is pretty slim. The odds of countries that hold US debt doing it are better. But there's a strong deterrent for countries doing that. And it's the reality that the US has no issue with invading, and they've done it countless times this past century to the applause of the voters.