Oh, he’s plenty calculating. You can tell that from his pre-2016 statements and actions.
Stated that if he ever wanted to win the presidency, he’d run as a Republican because that group is easier to manipulate (paraphrasing)
“I love the poorly educated.” He knew the vessel to get him where he wanted to go.
There are lessons from the Greek/Romans that he clearly understands, too: Control the “mob” (ie. The ignorant masses) and you control political power because of all the politicians that depend on that same mob for their own position of power.
Undermine any threats to ascendency- he did this early on by attacking the media and destroying our trust in what they say. He continues to do this against any person, organization or group that opposes him.
Keep the masses pre-occupied with shiny objects while you do your dirtiest work out of site and without scrutiny. “Bread and circuses” if you will.
And finally, “flood the zone” - he throws out so much crazy and (sometimes meaningless) shyte that no one can keep up with all of it and those who try eventually become fatigued and have to disengage or let it drive them insane. Either way, it’s a “win” for Trump.
So is he Dumb? Probably not. But he is definitely an immoral, narcissistic, sociopath with an extreme obsession with fame and fortune.