Honestly, I don't know what you consider a diehard. Everyone I know that is voting for him is aware of his dark underbelly, but, being adults, realizes that he is an exponentially better choice than Harris. That is just how unqualified she is for the job. And we already know that he's not going to usher in the Apocalypse. I'm essentially saying, to the left, "don't vote like a silly child" That's it.
The Democrats though, need to wake up to this reality: You all played a much bigger part in Trump's popularity, than the far right fringe that you like to portray as a huge part of Trump's base (which it is not)
You had this guy beat, and you wouldn't let it go, and now you've brought this upon yourselves. That is the cold hard truth, so you don't get to cry about it now.