But obviously the question isn't "would they still want dollars?", right? But rather "at what price (i.e. interest) will they want dollars?"... and my point is that price will need to keep increasing as the US borrows more and prints more money to pay interest on its existing debt, right? I don't understand how you just neglect this feedback loop... it screams exponential growth to me.

You are absolutely correct. If demand for dollars drops someday the U.S. is in for a world of hurt. It would have to find some way to decrease the supply of dollars to match. Right now I believe that would have to be through increased taxation.

I'm saying that on the current path the US is on, it's not "if" to me, but "when". Or to be more precise, "at what rate". And I see that rate as monotonically getting worse.

And either way, then doesn't "nobody in the field worries about hyperinflation for developed economies" seem utterly misguided? It seems quite worrying given what I just described.

So, buy bitcoin!