A friend of over fifty years visited me recently. He has appeared in a number of films and has lived in Hollywood part time. As our conversation went from recalling old friends to current affairs I was aghast as to how shallow he had become. As he would set forth some astonishing opinion or conclusion, I would ask him for one or two facts to back up his opinion or conclusion and he would say he didn't need facts and that the opinion or conclusion was self-evident. After more than day of this, I told my wife that I didn't know whether I could cope any longer.
I should note that in high school this friend was above average in intelligence, if not in grades.
That's interesting. It's probably a common pattern, too.