I am honestly baffled what this whole shitstorm is about. Like why did Trump want to bash on Canada in the first place? None of his purported reasons pass the laugh test. Fentanyl trafficking? As has been widely reported, less than 1% of fentanyl that has been caught enters through the Canadian border. And if Trump cares so much about drug trafficking, why did he pardon the Silk Road founder, which did over $200 mill…
I don't think there's a point in looking for a rationale. His mind is exceedingly addled and he's even less coherent than he was during his first term. Combined with delegating responsibility to a bunch of people high on various drugs constantly telling him to do X or Y or Z his policy is 'whoever talks to him first'.
The reason that he came out of the gate so hard is due to extensive planning, and he's the only person during your lifetime who was the president, had four years off to reflect on it, then became president again. He recorded weird little videos of all of his future policies a couple of years ago, and he's not deviating from them significantly.
He's the least confused guy in politics right now. Whether you like it is a different story, but I personally am thankful that the worst, covert elements of the government made an enemy of him in his first term. The obvious temptation when handed a dystopian nightmare of surveillance, censorship, front groups, fake science, and an infinite mandate to the executive from Congress would be to use them. Thank god Trump actually hates them personally, and is petty.
Economically, he's sincerely trying to keep the US from paying the piper for the trade deficit we've been running for 40 years. He obviously actually believes in this. It is also completely mainstream economic theory. I wish there was a political force that could oppose him on policy and say why things should be done a different way, but the "resistance" base is still announcing that the walls are closing in on orange Hitler any minute. Policy is like kryptonite to anti-Trumpers right now. They refuse to argue anything on the merits, because they all sound like Reagan Republicans when they do.