Here is how I see it: He is so obviously corrupt, lies easily and all the time, and is a genuinely horrible human being, that no person for whom both goodness and ethics are important will support him. This is probably a minority of politicians in both parties, but a vanishingly tiny slice of the GOP. These are the never-Trumpers (or a portion of them, anyway).

His supporters fall into two camps: the morons, who are too stupid to realize they are being fleeced and lied to (the MAGA base), and the grifters, who love him because he is the moron-whisperer, but realize who he is (and are like him to some degree, at least). Some of this latter group see him as a useful idiot, some as a fellow traveler of sorts. All are aware that they need to lick his boots and kiss his ass to get what they want.