Lack minded individual
A lack minded individual is a bunch of people who all think they're the only one who’s stupid.
My friend and his squad are lack minded individuals. They think they’re the only ones who failed the test.
My neighbor and her friends are lack minded individuals. They all think they’re the only ones who don’t know how to use a remote control.
My brother and his friends are lack minded individuals. They all think they’re the only ones who can’t do math.