Occam's razor: The simpliest answer is likely the correct one. He's a narcissitic dolt who is deeply resentful of an imagined "elite" that rejects him, and doesn't really know what he's doing, but taking bold action fills an emotional chasm even if only for a moment (in a sense recreating one of the two happy times in his life, The Apprentice (the other was his rise when Fred Trump was shadow managing his development of mid-town). There's other stuff, but at his core, he doesn't understand macro economics or the forces at play. LIke a 11th grade student who hasn't taken economics but taken American history, he thinks tariffs are good.
People forget that for all the drama of his first term, he didn't actually accomplish all that much from a practical perspective that actually impacted the bulk of the electorate's daily lives. He signed a tax cut that he had virtually no role in writing. He managed to get a few hundred miles of wall built. He got a covid vaccine into production in rapid fashion (i'll give him credit where credit is due), and the stock market mostly grew, or rapidly came back post March 2020. His attempts to radically change America mostly flamed out: either due to staff incompetency, or adults in the room thwarting him. Only post election 2020 did the real angry Trump grab the reigns and start implementing what you and I would call a basket of crazy.
Now he's unbound and surrounded by syncophants and enablers who know, mostly, how to enact his agenda. And we are getting it. All at once, without lube.