Batman is not a hero. He does what he does not to protect others but because he is an immature child. He never moved on from his tragedy, and he never learned to accept it. After all these years, he is the same angry kid he was back then. He beats up criminals out of sheer bloodlust and rage. If he wanted to stop crime, he'd use his fame and money as Bruce Wayne to fund social change and welfare. Instead, he perpetuates the cycle of violence which drives Gotham further into ruin. His vow against murder is not about morality; it's to keep his victims alive for more torment.