In fairness, it’s not really that far a stretch to have believed that Trump wasn’t going to actually build a wall, because his stated plan to build a wall was reallllly dumb. Like, on its face, it was totally implausible.
His stated plan was to have Mexico pay for a giant wall.
It wasn’t some kind of metaphor, either. His plan was that somehow Mexico was literally going to give us money for a giant wall.
That plan was, obviously, idiotic. It was never, ever, going to happen.
Now, for a more rational voter, you might think, “Well, I’m not gonna vote for the guy who is pitching an obviously absurd, implausible idea.”
But apparently a bunch of Trump voters just thought that the dumb parts of his plaform (it was all dumb, but they thought SOME of it was dumb) was just a joke, and he was going to focus on doing the other stuff.
So ya, this guy is dumb, but he’s not dumb for thinking the wall wouldn’t be built as Trump suggested… because it won’t.