I think fear that if a Republican wins office it will be the end of democracy and we will collapse into a single party totalitarian system is probably unfounded, yes.

I suspect the Democrat party feels the same way behind closed doors, otherwise we wouldn't have heard their candidate at the time (this was before Biden quit) say “I'll feel, as long as I gave it my all and I did [as] good a job as I know I can do, that's what this is about." That's not a thing you say if you genuinely believe that this election is the last chance to save the country from becoming an authoritarian fascist state.

But really that's besides the point - the point is that both sides actively engage in trying to terrify their voters into voting for them because neither can present a reason why we should want to vote for them in remotely enough numbers to win otherwise.