Oh it's why his base votes for him. And his base makes up enough of the party now that any opposition gets run over.
There are many within the party (or just right leaning voters that dont necessarily have party affiliation) who vote for him because they simply cannot bring themselves to vote Dem, even though they dislike Trump plenty. I couldn't do it, not even close but I wasn't about to vote Kamala either. I feel I'm more the exception within the moderate right though, more just hold their noses and vote for him than not.
My point was more that he would rather split the vote as an independent than support someone else had he lost the primary. Self over party. And thus it became a self fulfilling prophecy because it was a game of chicken nobody every could've won against him because he wasn't bluffing. He'd take it all the way, making anyone truly challenging him moot.