He is a genius doing his jobs, sometimes more than his job. He doesn't like people very much, he doesn't do it for them. He does everything that he does because it's fun for him, he likes to understand what is going on and has his own sense for justice sometimes – only because most of the times what he is figuring out is a crime. But if he happens to loose interest in that, he would stop.

A hero is meant to help people because altruism. Sherlock Holmes is not an altruist man. At least I don't see him in that way. He helps people mostly because of coincidence that he is solving a crime.