Trump has proven to everyone that most Republicans don’t actually care for “family values” or even obedience to the rule of law, provided they get what they want out of a Presidential administration. That’s changed not only the political landscape, but also Republican tactics in general: now they don’t have to conceal their nature, and can go full-tilt authoritarian without it costing them support among their primary voter core.
The GOP can’t trust Donald Trump, that’s for sure, but they know that he’ll play primarily to his own interests – and, in doing so, he’ll benefit them in the process. Changing candidates not only means having to face Trump as opposition (and therefore risk losing the support that he brings), but also means that they have to change their approach.
There’s no point getting another candidate like Trump when they can just have the original version.
Sisyphus Shrugged 