I can't stop making fun of people and I don't know why
You really doing that? What are these people doing that causes you to want to make fun of them?
Multiple things, they could be stupid, ugly, fat, annoying and a whole lot more.
It is pretty messed up to make fun of people repetitively like this. Maybe instead of all the rude comments, you could try swapping in a compliment every now and then to break the habit.
I don't think I can do that, it's too hard and my comment sections are just a joke.
If it's too hard to not make fun of people, how about just trying to shut off social media for a while? It can say a lot about yourself if you always do this, so why not try to remedy it by trying out a therapist? They can help you learn to be nicer to others.