I think you actually _should_ assume that he's acting rationally, just that his motivations aren't aligned with what you think they should be. Trump has a mafia mentality, and the purpose of the tariffs has absolutely nothing to do with policy and everything to do with control. He wants to have a guillotine hanging over the head of every country and corporation that he can use at will, so that every CEO has to come to him and bend the knee, so he can grant them an exemption on a case by case basis in return for personal loyalty to _him_.

There is a reason that the power to tax resides in congress, and it's specifically to prevent that. They've just abdicated their role and here we are with a king instead of a president.