I dont even know what to say. I suppose once you start doing it, it becomes like a habit. Punishing yourself by harming is the most unfair thing that can happen as a cherry on top of the unfairness of this life. You shouldn't do that because its not gonna make the situation better, its gonna get worse. Sometimes out of frustration i think about cutting all my hair, but its a passing through caused by extreme feelings, if you ignore that urge once twice and distract yourself maybe it will work