Stupid people don’t know they are stupid because they have no frame of reference. They are easily convinced that they are smart and often go around feeling very smart because they did something that they saw as clever even though it might have been accidental. Things that stupid people see as smart are not as smart as the things smart people see as smart. Smart people also realize they are capable of stupidity while stupid people don’t know how stupid they really are.
Social media is the number one spreader of social stupidity.