Because they couldn't cheat in 2020 due to Covid, it wasn't the candidate necessarily. They stuck with Biden as long as they could until his debate debacle.
I'm as pessimistic as anyone, but so far, this has a different feel. It hasn't gone away, and seems to be growing. The media, so far, isn't falling for the distractions. There are a handful of Republicans not letting it go. Will it take Trump down? Probably not, and it'll probably be the Dem establishment who lets it go because Clinton or some Hollywood donor is on the list. The other hope is that the walls closing in will stress him out enough for nature to take it's course.