What if you're wrong? What if the apparently irrational behaviour hides a well planned policy that has desirable outcomes for someone?
What the US really wants imo is for Canada to tariff Mexico so we can remove the Canada tariff without undermining the Mexican one. Pretty much guarantee we'll see Trump pushing Canada to do that in the upcoming negotiations.
Mind you, I don't know if Trump has thought that far. But "own Canada, but good bye ruling majority"? I'm not sure he really wants that.
Obviously I don't have access to Donald Trump's brain, so I am only able to judge things from how they are. How they are, at least right now, seems to indicate a completely economically illiterate person.