I know he’s surrounded by yes-men, but is he really that sheltered?

More than you might think. They're not just sycophants, but people who have now gotten jobs in or near the Oval Office itself, working for a highly volatile, unstable man-baby who screams at and fires people on the regular just because he needs someone to blame. I'm sure some of them, especially the younger ones, are traumatized.

So it's everything you said, but add some terror and the threat of losing everything you ever worked for, and that's the level of information filtering he is surrounded with. Nobody's going to tell him what he doesn't want to hear, especially if someone else can do it, and in the end he just doesn't get told a lot of things.

This is the one shiny thing about Stephen Miller getting the Chief of Staff job: he's no Susie Wiles, and he's now going to be the personal target of all that demented presidential ire. Whatever happens from this point forward, at some point it's all going to be Miller's fault even to Trump, and the ketchup will fly, and he too will be thrown under the bus.

(Note that Miller was also left on the decoy plane when Trump and Natalie Harp left via food truck to get on the real Air Force One in Turkey: to Trump, Miller wasn't worth saving. None of them were, except Harp.)

Remember the hurricane prediction map that they drew on so he could be right when he said it was going to hit Alabama (or some other gulf state).