Why is Self-Expression Being Laughed At?

There are many ways to express yourself. Whether it be through painting and drawing, music, dancing, sports, writing, etc.
So why are these forms of self-expressions mentioned above (as well as many others) being laughed at by peers around you? Just because you play the trombone in the school's marching band, why does that have to be so dorky? What if, instead of pumping iron in the gym or being on the basketball court, you liked to write stories? And why do you have to be mushed into a little group of people exactly like you just because of the music you listen to or the clothes you like to wear?
And it's not just the arts that are being laughed at either. Sometimes, certain sports are being scoffed at too, for example, tennis. My dad used to be on the tennis team at his local high school, and because of the sport he played, he became unpopular. No matter how good he was, it didn't matter to the football and basketball stars of his high school.
We're all different and we all have different talents and abilities. Most importantly, we all express ourselves in different ways. Why should we label and write people off if they're on the basketball team? Why should we call someone a freak just because they like to draw manga?
I think we all need to take a step back and honor everyone's talents and abilities. I think we all need to see that labels don't matter, and just because someone likes a certain thing, doesn't mean ALL they have to hang out with is people who are interests are the same. Why can't we all just get to know people for who they are and despite the differences, try and be friends?
In spite of our differences, those rare moments when individuals come together to make a difference is true expression itself.
Okay, mini rant over -____-