Can't it be both? Sometimes he just says stupid things off the cuff because they come to his mind and he just blurts it out, but I do agree that he sometimes has a little more motive behind certain statements. When I said "I think the idea that Trump is some diabolical mastermind is, for the most part, giving him too much credit." -- Trump's skill with the media was one of the big things I was hinting at with the "for the most part" caveat, and I only had that vague caveat at the time because it's still hard to describe Trump's skill with the media.
He's good at playing the media, but that shouldn't be confused with suggesting he controls the media's narrative about him. He's really good at getting a lot coverage, and most of that is usually bad coverage, but that's sometimes still helpful to him if the bad coverage is about something silly instead of something serious. For the people against Trump, it's a pretty effective distraction. For the people that are pro trump, the silly stuff is easy to dismiss and it just feeds into the media being the enemy of the people narrative.
But my current thinking is that he's using this skill in a pretty blunt way and doesn't have full control over his power. His skill with the media seems to mostly be a consequence of him having no shame and a lot of experience in reality television. In entertainment, 'there's no such thing as bad publicity' probably has some truth to it. In politics? Not so much, and I'm not sure Trump knows the difference. For Trump, he embraces negative reactions if they're coming from the right audience -- not just embrace, but seeks out -- if he's pissing off liberals, he thinks he's winning. It fits within his transactional view of negotiations too, where one side is winning and the other side is losing, so you're not doing it right unless the other side is complaining. Sometimes he fucks up and gets a negative reaction from the right, so he tries to fix it -- and that fix is often something that just makes him look even worse to the left (so he appears even more incompetent to the left), but it works for the right (so his base gets back in line).
It's useful to think how a smart person would use that skill. Basically, a smart person wouldn't be digging themselves in these holes in the first place -- wouldn't be making so many mistakes -- wouldn't be so sloppy. It's a powerful skill, and he's getting some value from it, but it'd be a lot more powerful in the hands of someone that wasn't such a big fucking idiot. And some smart people on the right are paying attention to this, and that's scary.