USD strength comes from military. Just as it was the case with all other currencies in the past. Do you see anyone challenging the US in a conflict? China won’t even invade Taiwan because they are afraid. ‘Nuff said.
Because it might not work out so well for them? Let's not kid ourselves, this would be an invasion by sea against an opponent who's prepared for many years, has a modern defense force, and has explicitly designed a defense protocol to inflict as much damage as possible. This is not Russia stepping over fields they already encircle that are governed by a dysfunctional government. And it's not Isreal being allowed to bomb impoverished children with impunity either. And neither of those scenarios have worked out splendidly for them either.
Slightly less compressed, it should be "When a nearby state keeps saying they own you, then take the credible threat seriously and pretty much pretend they're going to act on that, even if you think it would be stupid of them to do that, because history is full of examples of states doing this kind of thing. Prepare accordingly".
Those around the president have been pretty clear that the US will defend Taiwan until the US is capable of its own supply of leading edge semi conductors. Taiwan is very easy to defend with the harsh ocean separating them, especially since North Korea gives the US an excuse to plant massive amounts of long range missiles in SK.
There are no surprises when attacks start in the era of real time world video satellites.
Basically, when China is at maximal power relative to the US. Most credible commentators in the West say that'll be in 2027.
The only realistic options that exist at the moment are going back to the gold standard (not viable for most countries) or shifting to the yen (which is tied to the dollar as Japan is the largest holder of treasuries).
It will be more costly for the people doing this later, of course.
Liberals are like libertarians in this regard. Housecats that don't understand what the actual source of stability and prosperity is.
"But what about the stuff that the factories import, to produce anything?" one might ask. Well, Trump wants no such imports - he wants the people selling stuff to the US, to relocate to the US.
Note: I'm not in favor for what Trump tries to do, but it explains why there's so little concern for the dropping dollar.
US Treasury bonds will be less attractive, because foreign investors will lose trust in the US economy