I agree with this explanation

David Roberts at Vox:

Trump isn’t an evil geniusAnd that’s not what matters anyway.

My theory is that authoritarian demagogues are more alike than they are different. Most of them are narcissists. They are, at root, fearful, paranoid, and tribal, which drives the macho posturing and obsession with loyalty. They have a kind of animal cunning for how to manipulate people, dominate, and accrue power.

But for the most part they aren’t evil geniuses. (One of Russian journalist Masha Gessen’s recurring themes about Putin is what a “grey, ordinary man” he is.) Indeed, evil geniuses are pretty rare — or, to put it more precisely, narcissistic, paranoid tribalists are rarely geniuses, because genius requires a certain detached perspective, an ability to step outside oneself, which is precisely what narcissists lack.

What authoritarian regimes do is blunder forward, grasping and grabbing power whenever and wherever they can, building secretive inner circles, surrounding themselves with supplicant state media, demonizing dissenting voices, and punishing enemies. They do this not because of some 12-dimensional chess analysis of the political landscape, but because that’s what narcissism and zero-sum thinking does. They are more like animals driven by instinct than chess masters driven by strategy, though of course there’s a range (with Trump being on the far blinded-by-narcissism end).

If we’re looking to understand the course an authoritarian takes through a country and its history — what’s he’s accomplished, what’s likely to happen next — the place to look is not his intent, but the institutions and norms of the country he seeks to dominate. They, not his ultimate goals and desires, are what most determine the ultimate shape and consequences of a regime.