Good to know everyone making games are kids. It would be a shame to know that grown-adults were actually spending time playing, let alone making, video games.
No, of course it's not something you "grow out of." It's a hobby, like anything else, and it holds interest for the individual as long as they allow it to. If it no longer interests someone, they'll drop it, but it's not because of getting older. Until games become the equivalent of pulling on a girl's pigtails, I don't think it can be considered something you grow out of.