I think some of them obviously do - did - at some points, and at the same time, it would occasionally be clear that some of them were also out of touch with reality. But having pathology in a position of power is evidently known (to specialists) to create a sort of cult of personality and spread the disordered thinking to followers that they accumulate - Dr Bandy Lee has posted about that on Twitter as well as in various articles and op-eds she's written over the last five years or so. I gather it's also touched on in that book by mental health professionals called "The Dangerous Case of Donald Trump", but I haven't read it.