It's a lot like his businesses back on the day. He tried the well being of something larger to him personally, so that a lot of stakeholders are desperate to bail him out specifically lest their larger concern is tanked. When his properties were in trouble in the 80s, investors/creditors helped boost his reputation because that was the only hope to salvage their money.
Here he made it so the entire Republican party will succeed or fail according to his personal situation. So desperation to mitigate his personal mess for the sake of their precious Republican party.
I know a registered Republican who has never voted for the Republican candidate in the general election.
She says she agrees with the concept of fiscal conservativism, but every candidate she votes for in the primaries always loses to some intolerable asshat. Except she did like McCain, but she liked Obama even better.
Trump pushed her so far as to donate to the Democrats, but she is still registered Republican.
I know another registered Republican who did vote Republican back in the 80s, but at least says he hasn't recently, similar reasons. He stays Republican mainly because he doesn't see any point in bothering to change. Where he lives is die hard red so he knows the Republican primaries are his only chance to influence any candidate as even if he likes a Democrat, they will automatically lose. He votes Democrat in the general, but considers participating in the Republican primaries his best shot at mitigating the bad of the modern Republican party.