When you have a social life you devote so much energy externally that you leave none for internal persuits. People who never have time for introspection end up being hollow. Normal guys might be funny or even sociable but they often dont have very compelling personalities, and if you think who you talk to or how much socializing you do gives you a personality - you are unfortunately normie too

Normies latch on to stuff like being otaku, because subconsciously they yearn to have a personality and interests that are not solely based on social, things, so they imitate.