I think you are a troll or a deeply disturbed person. As a fairly disturbed person myself i am not really judging just pointing out that you should look into your own psyche a little, though it's dangerous to do so if you are truly satisfied with yourself and your life, i wouldn't chance it then. But if you do find things lacking, i would do some research into various mental disorders relating to ego, and whatever else you feel might make you different than others.
Being nice has its advantages. I imagine you are nice when you around people that are threatening or people that have the ability to give you something you want. Maybe you can learn to be nice to people on the chance that they may in the future give you something you want or that the people around you will see you being nice and think better of you, giving you more options when it comes to dealing with them.
Also, lastly, you can learn to enjoy being nice. See being nice as its own reward. That would truly be actually becoming nice. That seems like it might be a big step for you, but if you can do that you will get some benefits from it. People aren't nice cause they are nice, they are nice cause it feels good. It also happens to be good for you. Feeling a sense of belonging and connection to your surroundings, even if they are virtual strangers on the street or at the store, is good for you physically. Lowers cortisol and increase dopamine etc. etc.
So really see it as something you are working on for yourself, not for others. The added benefit or cherry on top, is that it will probably make others feel good too.