Yep, but my point is that one is mass belief that the US government will continue wanting USD, the other is a mass belief that other people will continue wanting BTC. Both could be right, both could be wrong, but they are not the same proposition.

Don't forget that the US gov itself is also propped up by mass belief. Its authority rests in the people.

Now you might say "actually its authority rests on people with guns", but that's only to the extent that the people with the guns believe in the governments's authority to tell them who to point them at.

Underneath all is belief and sentiment.