I think they see how dropping Biden has significantly benefited the Democrats and hope the same would happen for then if they dropped Trump.
The problem for them with that is that Trump will never willingly step down. Unlike Biden he’s in it for himself and has everything to lose its he doesn’t win. This would also be guaranteed to result in crippling infighting in the party and with Trump trying to go independent.
The Republican party is f’ed. That’s what you get for selecting a selfish lunatic to lead it.