Probably, because they are neither smart nor intelligent. Those who are highly intelligent are usually intelligent enough to stay quiet about their cognitive strengths. (There are, of course, exceptions, but they are the exceptions that prove the rule.)
From the time they are young, highly intelligent people receive praise for their prowess in school and recognize that they have some cognitive advantages over most others. They also learn very quickly that promoting themselves and their intelligence often results in hostility, ostracism or being bullied. Consequently, most of them choose to stay relatively quiet about their gifts.
Those who brag about their intelligence and put down others, are either highly intelligent people who have not learned social skills or, more likely, people of average intelligence who seek to convince others that they are smarter than everyone else.
When Albert Einstein was asked by a reporter what it felt like to be the smartest person in the world, he answered, “Why don’t you ask Nikola Tesla?”
Charles Darwin, who changed our understanding of who we are and where we came from, modelled the humility that comes with high intelligence, confessing in his memoirs:
I have no great quickness of apprehension or wit which is so remarkable in some clever men, for instance, Huxley. I am therefore a poor critic: a paper or book, when first read, generally excites my admiration, and it is only after considerable reflection that I perceive the weak points. My power to follow a long and purely abstract train of thought is very limited; and therefore I could never have succeeded with metaphysics or mathematics.
