This is so true.
“Given his personality, he strikes me as exactly the sort of very intelligent person whose assumes that their mastery of one field (effectively science-and-engineering, along with magic-and-persuasion, in this case) makes them equally able to perform in other, completely unrelated fields (a mistake common to very many very smart people, but – it seems to me, though this may be only because I work in the humanities – peculiarly common to those moving from the STEM fields to more humanistic ones, as Saruman is here). I immediately feel I understand Saruman sense of “I am very smart and these idiots in Rohan can command armies, so how hard can it be?””