Why are people bullying "nerds"

And by nerd I mean kids who do well academically. I've actually never seen anyone bully smart people around me bro, but I see it all the time in western movies. Even online, I saw a video of a kid who could calculate really fast, i think he set the world record, and people in the comments were dissing him saying that he probably has no social life. Wtf ??
The stereotype of a "ugly nerd character" in western movies, very different than asian media, where the bullied nerd is usually an otaku and not the super smart guy.
even the popular kids in my school were the ones who were good-looking, good at studies, good at sports, a Mary Sue type of person. And the good at studies was the crucial part here, you could look like a celeb and kids wouldn't hype you up but if you were mildly attractive with good grades you get treated like a god or smth.