I'm convinced Trump is 100% sincere in his belief that his economic ideas are brilliant and will lead the US to a golden age.

I think his (and much of the far right's) mind is characterized by:

- a deep incuriosity and unwillingness to learn about the world

- extreme overconfidence in his own judgment

- an understanding of the world as being pervasively zero-sum (shared with Putin); your loss = his win

- obsessive preoccupation with the dynamics of humiliation: he feels an extreme need to be perceived as strong and to humiliate his enemies, and he greatly fears being humiliated

I feel like these characteristics explain most of his policy. The idea of tariffs arises from his zero-sum mindset: the only way to gain is by making someone else lose. This is of course factually wrong, but he's too incurious to learn from history or economics. And, of course, he's massively overconfident, so the thought that someone else could know better does not occur to him. And once the ball is rolling, his fear of humiliation will ensure that he has to stay the course. His perceived enemies (which is everyone) have to come crawling to his throne, begging to have their tariffs reduced while praising his brilliant policies, and then he might consider it. So if that doesn't happen, his only options are (a) perpetually retaliating with ever-increasing tariffs, disregarding the consequences entirely; or (b) capitulating in the trade war (lowering or abolishing tariffs) while not admitting that it's a capitulation ("don't worry, my brilliant policy fixed the mass influx of fentanyl and illegal immigrants from Canada, so now we can drop the tariffs on Sri Lanka" or something similarly incoherent).