He’s not smart in the book sense but he does know how to play the game. For example, if you listened to the audio of his call to Zelensky which lead to his first impeachment investigation, pay attention and you might notice he avoided being explicit with his quid pro quo and spent the whole conversation beating around the bush and using weasel words to try and get what he could out of him without implicating himself. Even if the Senate trial wasn’t openly a farce, he still would’ve been found innocent because for something like this you have to be able to prove intent and that’s extremely difficult unless you blunder your way into an explicit admission of intent to commit a quid pro quo somewhere along the line, which he didn’t do in the audio of the phone call. I’m not saying it’s wrong to be suspicious because that call was obviously shady as hell, but it was never going to meet the burden of proof.

His propaganda and overall rhetorical strategy are similarly manipulative. It’s very common to mistake his lies for being stupid and obvious and assuming that’s just the end of it when in fact it’s actually a very specific rhetorical strategy called firehosing. The idea behind firehosing is to flood the entire system with too many political narratives, misdirections, pivots, red herrings, strawmen, contradictions, and controversial statements to keep up with so that everything is up in the air and the less regard for truth and consistency you have, the more effectively you can pull it off because the goal is to overcome reason with aggression while simultaneously drowning out opposing narratives and/or fact checking with sheer volume and repetition. It’s kind of like gish galloping but on a much more broad and ambitious scale, or if you’re as much of a gaming nerd as I am it’s the ‘zerg rush’ of political rhetoric. This explains why his falsehoods are so effective despite being so obvious - ironic as it looks on the surface he would actually be far less effective if he vetted his own bullshit and tried to make sure everything he said were at least semi-close to being believable.

Tl;dr, he’s a moron at some things. Manipulating millions of people and accumulating power at their expense (and ours as well even if we see through it) is, unfortunately, not one of them.