Why so people think I'm so mean?

m a smart guy and I get good grades, I never skip classes essentially I'm very education oriented, I have lots of friends or at least people I can talk to and hang with. Any way people have been saying now for a while that I'm a douche to people or I'm mean person, but I do try to be nice to people I'm not out to get anyone, my mouth gets 3 steps ahea of me at times and I say something that I think is funny an no one else does they find it offensive, that doesn't happen often though. My friends say I'm a douche because I'm mean to others and act like I'm more intelligent than eeryone basically people think I'm cold and stuck up, I don't try to be it's just that my focus is generally fixated on getting good grades an not getting involved in the whole ******** part of highschool, you know, who did what whose popular, I think maybe I'm more mature than people or something, idk I can't figure out why people think I'm a douche,