To be clear, being a Ninja is a job. One you are not paid for and you do on your free time. It also isn't an endgame goal as many people think it is. Nor is it a popularity contest. If you want to be a Ninja there are several factors that come in to play. For one, you have to have a good understanding of the site and app. You need to be able to make good judgments on what topics belong where. Secondly, you need to be invested in pretty much all aspects of the community. You don't need to be popular, that's not what it's about. But you have to at least have a basic understanding of the sub-cultures of the entire community. Most importantly, you need to know the rules and be a good example of someone who upholds those rules. The Ninjas use their best judgment interpreting the CoC since they're relatively broad guidelines. Bungie does not just hand out Ninja status, there are periods when they decide to chose users to join the ranks. In fact, an old rule (no longer in effect if I'm correct) was to never ask to be a Ninja. They choose users based on the fact that said users uphold the qualities and standards Bungie wants from the community. They are not just moderators, but examples to the rest of the users on the site.