Personally, I wonder if it's less "party of Trump" and more "party of Winning".
A lot of Social Conservative policy is terrible for business (How much money was lost by states chasing those 'Bathroom Bill' regulations?). A lot of pro-business/Fiscal Conservative policy is difficult to square with traditional moral values (You want a traditional household with a full-time parent, but can't figure out that low wages make it impossible?)
Both factions seem willing to ignore this because they know they can win elections by their combined might.
I suspect if you look at it, you'll see that the party platform has become progressively more narrowly focused and sloganized as a result of that. Focusing on abortion and gay marriage to the exclusion of any more nuanced social issues throws a bone to the morality crowd without having to let them ask "isn't unconstrained billionaire greed a sin?" Simplifying all financial policy to "taxes bad" is pro-business but not as offensive to the morals crowd as admitting "systemic racism is probably leaving a lot of money and productivity on the table"
I suspect backing Trump is just further reaction on that scale. It worked once in dramatic style (they won an election largely seen a formality) so they're doubling down on it.
However, I'll say the same thing applies to a degree on the Democratic side, in a variant form. They've decided to go for "broad appeal" rather than "a few specific silo niches", which results in milk-toast moderate candidates that can't possibly offend anyone.
What's interesting is that any electoral success for either of these paradigms just reinforces them, but any failure never seems to cause rethink.