That's part of it. He believes he'll be wildly successful regardless of domain expertise. He's so smart and anyone who questions or doubts anything he proposes is a worthless idiot.
There couldn't possibly be a good reason for things being the way they are, and he can't be arssed to stop and learn before loading and firing off a tweet from his gigantic ass cannon.
Whatever it is it's the same thing Trump has. They assume every problem is extremely simple and for some reason they're the only ones who see that, while everyone else is screwing things up by making everything complicated for no reason. So they dive in without a second thought and are surprised to find out things are more complicated than they assumed. That's the charitable story.
The less charitable one is they love getting points from their fans for calling everyone dumb and saying they can fix everything, knowing ahead of time they can just keep changing the story when things don't work. And their fans do in fact give them points for what they say about what they'll do in the future, every time, without even looking at the track record of previous such statements