One of my classmates needs a tutor, but I am not going to.
Who exactly asked you to tutor your classmate?
The teacher I mean, he's terrible. He's a total loser and the other students do the job better than him.
You should go the extra mile to help out your peers in learning. Every student deserves to have the best education, even if your teacher can't provide that well enough.
Maybe, I did it to prove to my classmates that they should never listen to him.
I am telling you that you seriously need to reconsider and help this student. How would you feel if there was no one willing to help you? Learning is hard, but with a good tutor it could be much easier.