I think a lot of Americans did see Trump as an existential threat and that's why they voted for him. He was the "blow everything up" candidate, Harris was the "everything continues as it is" candidate.
This is literally the most charitable thing I can say about a subset of Trump voters. They actually did have a point there. A lot of people voted for Obama because he was the change candidate and this time around Trump was the change candidate. Almost entirely bad changes, of course, but some people were so desperate for change that they figured it was worth rolling the dice.
Just a subset of Trump voters, mind. Most of them were probably just awful people who saw a fellow awful person on the candidate and went "me like." But if a subset had decided not to vote for him we wouldn't be here now so they were significant.
Yup. The "you can't make an omelette without killing a whole bunch of people" mindset.
The annoying part is that it's not entirely wrong, IMO. At this point I think the best hope America has is for those Trump voters to feel the pain of the situation they have brought upon themselves, and for the Democrats to be pushed far enough to finally shake off the DNC establishment. America needs another Roosevelt at this point and there's no way someone like that would have got on the ballot or been elected under the past few decades' conditions.
Sure would have been nice if everyone had just been smart about all this and we hadn't got here to begin with, but we go to the ballot box with the electorate we have rather than the one we hope for.