I would stay on the site and try to hold my ground and help the site. If I were to lose the #1 rank I would do the same thing. And I would be proud of the person who passed me.
I would either realize how much time I waste on the internet and get off of the computer once in a while. Or I would just stay and continue doing what I did. I don't think myself better than anyone else and obtaining that status and holding it isn't that important. Besides the fact that you get a lot of spammers and people that stalk you, it's really quite annoying. I would continue to help the site as I always do.