Why would you

Because something it's better than nothing, I guess. When we feel pain we feel. It helps us to remember we are alive and who we are. I got used to feel pain constantly. Now it'd be too weird to live without it, It's like somehow you can get addicted to certain kind of pain. You may not really like it, but deeply inside you need it. You need to calm that strong anxiety to feel. You need to feel something. 

It may seem quite crazy for people who don't see things the way I see them. Some people could think that you're a poor thing hurting yourself in purpose. There are many many ways. But, what is to hurt? Just trust me, after all the pain I've been through this is nothing.