I don't see him as an idiot. I think he's a very clever and very nasty man.
Economically he's doing disastrously for the US. Sure, the economy is booming - that's what happens if you pump in trillions of dollars of newly printed money at the height of what was already an economic boom. There is a special place in hell for the congresscritters who blustered and protested about the deficit during the Obama years, but are happy to stoke it up now that an (R) is in the White House.
(Mind you, this is exactly the same as they did under both Bushes, and Reagan. It's why Clinton balanced the budget - it wasn't any particularly great management on his part, it was the Republican congress trying to crash the economy.)
The trade wars were completely unnecessary, and kicked off to make Trump look tough, while leaving open the option for him to declare victory whenever he wants. Take China, for instance - he's never spelled out what it is he wants the Chinese to do, so anytime he feels he wants a victory, he can simply announce that they've given in and the war is won. Of course, that's given China some leverage over the US that it didn't previously have - it can demand concessions from Trump to back up his bullshit - but that's fine - Trump can profit from that too (as in the present story, for instance - he's just created a whole new channel for himself and his henchmen to receive kickbacks, that's what "licenses" mean - as Republicans would be lightning-quick to point out, if it was the other side doing it).
Don't get me wrong, I think Obama and Clinton were both pretty poor presidents. But at least they had some respect for the ideas of law and democracy and republican government. Trump is a whole new level of two-bit, four-flushing, slimy, cheating turd, but he's pulled off the remarkable confidence trick of convincing over 40% of US voters that he's in some way "on their side". Anyone who thinks, at this point, that he's stupid just isn't paying attention.