I certainly didn't mean everyone - after all both my parents, my sister and her husband have doctorates and they aren't like that (My father is a weapons grade arse hole but that's not related to his doctorate). However particularly in academia (rather than those who work in other fields having achieved their doctorate) you do periodically get a Dr who thinks his or her PHd gives them a far reaching insight , not substantiated by their intellect and ability. I think this is partly because they spend a lot of time as the 'most intelligent person in the room" when lecturing to under grads , and think this carries over into real life.
An absolute classic case was the Doctor (of art History) who's complaint I dealt with while working in oxford , who wanted to know why we had not pumped the flood waters off Christchurch meadow into the storm drains which would apparently have been both "easy and simple" , and he was "surprised it took someone of higher intellect to point is out"
Having had the misfortune to deal with a number of similar individuals , I can confidently say that he is not an isolated case (though of course nor are these individuals the absolute norm) - nor is this a soley British thing - I have a friend who works in Cambridge, Mass , and she reports a similar level of Bellendery associated with some professors at Harvard, Tufts, Taft , BC and so on