You keep making the mistake of conflating the 2016 RNC's political fortunes and Trump's. Many Republican insiders probably didn't even want Trump to win the general election as it would mean they'd be frozen out of influence in the party. Remember that guy Paul Ryan?
After Trump was elected and showed himself to be an establishment wolf in populist sheep's clothing they've largely mended relations, and the few holdout never-Trumpers have left for other pastures (including the Democratic Party), but it was a very different picture in 2016.
> You keep making the mistake of conflating the 2016 RNC's political fortunes and Trump's.
You do realize they were on the same ticket, and Trump's fortunes on that ticket had direct, downticket nationwide consequences for the rest of the party?
You only need to look to the UK's Labour Party for an example where a certain faction of a party's insiders considered it better for themselves for their candidate to lose a general election. Winning is never the only consideration.
After Trump was elected and showed himself to be an establishment wolf in populist sheep's clothing they've largely mended relations, and the few holdout never-Trumpers have left for other pastures (including the Democratic Party), but it was a very different picture in 2016.