I've had this view back in high school and in my first year of college. I've changed it since.
You may see their trendy clothes, music, slang, or whatever. That they like to drink or party. Or they go to a frat/sorority organization. Or they watch popular TV shows you're not into.
These are all superficial outer layer stuff. You don't know them on a human level. They could be a great friend, a great lover, or a great family person. They could be very kind. They could have lots of meaningful life experiences that turned them into a good person. They could be doing charity work or taking care of a sick family member for all you know.
And you may conclude. They're part of the homogenous trendy people. I'm different! I'm unique. I'm the black sheep. I'm defiant. I'm the outcast, because I don't fit in with these people. I'm super complex and interesting.
"I'm unique and everyone else is homogenous" is an egocentric. It's ego. It makes us feel special by reducing everyone else. "It's not me being rejected; it's me rejecting them!".
Of course you know your own depth and good qualities. You've spend your whole life with yourself. But with your other classmates and such, you've only seen many of them at the surface level.