Haruhi- Because you don't want to live your life alone. Believe it or not, no matter how much you like being by yourself, you will get lonely, and if you have no friends there's no one to cure that loneliness, and if people still think bad about you, you won't be able to do anything with your life.
Haruhi- It sounds like you need to talk to Mori-Senpai. I know what you mean that it is very comforting, but if you want to get out more and see more things, I think we can help you make due with being around other people.
Haruhi- I used to keep to myself too, until I met the Host Club, and since then, I just kinda came out of my shy shell, you know. Just walk up to some one and start talking to them. They're not gonna kill you or anything. You might get put down once in a while, but you will find some really nice people.