A hacker is someone who knows more about a system then you do. Just like a newbie is someone who knows less. A hacker is a lot like a mentor. They have the ability to use a system better then you, and help you if they so chose. No one person can claim themself a hacker, because there is always someone who knows more about a particular system. Just like no one should claim themself a newbie, because there is always someone who knows less.