Trump proved that many of the party’s moderates and establishmentarians hate the thought of a True Conservative nominee even more than they fear handing the nomination to a proto-fascist grotesque with zero political experience and poor impulse control. That goes for the prominent politicians who refused to endorse Cruz, the prominent donors who sat on their hands once the field narrowed and all the moderate-Republican voters in blue states who turned out to be #NeverCruz first and #NeverTrump less so or even not at all.
Finally, Trump proved that many professional True Conservatives, many of the same people who flayed RINOs and demanded purity throughout the Obama era, were actually just playing a convenient part. From Fox News’ 10 p.m. hour to talk radio to the ranks of lesser pundits, a long list of people who should have been all-in for Cruz on ideological grounds either flirted with Trump, affected neutrality or threw down their cloaks for the Donald to stomp over to the nomination. Cruz thought he would have a movement behind him, but part of that movement was actually a racket, and Trumpistas were simply better marks.