So far as I can tell, Trump isn’t crazy. Nor is he “crazy like a fox”. He’s just stupid. And beyond being stupid, he has spent most of his life at the center of an entourage of people that have become experts in influencing and managing him. Given that this has landed him a nice livelihood and all the hot women he could ever want, it seems like he’s long-since given up trying to hold his own opinions, and trusted to the group.
And, I would argue, that creates the potential for him to become a really good President.
President Obama, for example, was a smart guy. But, he was also a partisan/politicized thinker. Party politics and partisan beliefs leave the realm of smart policy and enter the realm of religious doctrine. So while most things that he did were smart, he was always handicapped by his personal beliefs. The spread of ISIS, the Russian success in Ukraine, and Chinese expansion in the South China Sea can all, for example, be directly attributed to Obama’s inherent distaste for warmaking and conflict. (Not to say that a desire for warmaking and conflict are good, just that personal predilections reduced his option set for responding to these issues.)
Trump has no opinions or predilections of his own. One could maybe argue that he leans Conservative, but only because Conservative media is more sensational and uses a lot more fear-mongering. To a person with no brain, that is just better TV.
But if you remove Trump from his TV, then suddenly you have a blank slate.
When you put Trump in a room with experts and ask him to decide on whose opinion to go with, he may not follow the arguments being made - only picking up and then later misremembering a few snippets of data from the conversation that made him happy or sad - but he can read the body language of all of the people in the room to get a straw poll of who everyone else, who did follow the conversation, seemed to think won the argument.
If you let Trump interact with people one-on-one, then you’ll see him make idiot proclamations, because whoever last saw him will have gained temporary control of the United States. But if you block off access and only allow him to see real, non-political, career specialists in the topics genuinely at hand, then Trump selects from whatever all the other non-political, career specialists in the room thought was the best idea. And, given that those will mostly be smart and capable people, their joint approval is a pretty strong indicator that the argument really was the best argument around.
Trump may never have his own ideas, and he may never have any grand visions, and so there may never be any grand direction that he can lead the country in. But in terms of just dealing with the issues that pop up, day-to-day, on their own, he’ll always just select the best and smartest idea that comes before him, if it was presented in a group setting.
Overall, the quality of the Trump Presidency just relies on Trump not getting too bored from having to sit through tedious debates on topics way beyond his ability to understand, and rejecting the restrictions that are being placed on him to ensure that he only sees good data and only interacts with people in group settings.