Even though Ronald Reagan would be unlikely to win the Republican nomination today, his core message "Government is the Problem", is the concept upon which the modern Republican party (and whatever's left of conservatism) rests.
Conservative "thinkers" like George Will and his ilk once provided the intellectual backstop to this philosophy by arguing that everyone's ills could be solved by getting the government out of people's lives, e.g. the much-derided, much-repudiated concept of trickle down economics, but there are many, many more examples. This sold really well to just-hitting-middle-age Baby Boomers (mainly White) in the 80s and 90s who reaped the benefits of more money in their pocket while ignoring the fact that this was accomplished by mortgaging literally everyone else's future (not just the economics behind the social safety net, nor the effective running of government, but things like climate change).
It had, and still has had, enormous electoral success because the concept is just so simple, and enters everyone's head the moment they get their first check and ask
"Who is FICA and why is he taking all my money?" Instead of campaigning on initiatives that are difficult to explain, like why parts of the government need to grow or change, you just have to tell people you're going to make their lives a little easier by taking away government interference and oh by the way you'll also have more money because we're cutting taxes.
When this is your platform, of course, you don't need deep thinkers to sell it during campaign season. Reagan, a former actor, was of course the paragon of this, scion/failson George W. Bush its maturation, and of course Trump its apotheosis or nadir, depending on your viewpoint.
Of course, back in the day, the George Wills (and, later, Andrew Sullivans) argued that the dismantling of government could, and should, be done in an above-board kind of way. No corruption here. Privatization was good because of a deeply-held belief (ironically held by said "thinkers" without reflection) that the market would provide, and provide efficiently.
Anyone who's worked in private industry (which includes very few of said "thinkers") will, of course, tell you a different story. In fact, as Gordon Gekko (surely now a Republican hero) would hold, a little corruption and graft is not a bad thing if it's in the service of revenue and profit.
Ironically, it was the Norquists and Gingrichs who won the argument, over the Wills and Sullivans. Why bother with putting thought and hard work into determining how to dismantle the government, when you could just starve it of funds, yes, but also attention and competence, and let it fail on its own?
In the end, then, the twin influences of a) having an easy sales pitch and b) not needing to do the hard work of governing created a modern GOP that is populated predominantly by hucksters, failsons, and the kind of used car salesmen your parents warned you about. Sullivan can whine all he wants about "epistemic closure", and Will and his ilk can clutch their pearls, but the very theories of governance for which they provided intellectual cover resulted directly in the modern GOP having no further use for thought or intellectualism, in fact it turned out that hostility towards any thinking whatsoever was more important by far. The "intellectuals" have been thrown out, along with any semblance of good governance, and they/it are not coming back. You'll get Ben Shapiro and you'll like it, essentially.
TL;DR: The modern GOP exists solely to destroy the government and make a buck along the way, and it has convinced its constituents that this will make their lives better (narrator: it won't). There is very little about Republican policy/actions that is not adequately explained by this. And since it's the product of 40+ years of development, it's not going to change anytime soon. Dwight D. Eisenhower isn't coming back to save us.
