So yesterday I ran my D&D game, which we have been doing this campaign for over 2 years now. I've been DMing (that's Dungeon Mastering, which is basically the referee of the game for those who don't know) since I was 16, so 25 years of my life I have been into role-playing. And not just D&D either: Shadowrun, Earthdawn (which I'm about to start up a campaign for tonight with some friends), PnP WoW, the list goes on and on. It has been a major facet of most of my life.
When I was a kid, admitting you played D&D was the social equivalent of saying that you were OK with being a loser. Not saying that's how I thought of it, but that's what most of my peers and society thought of it as. But, even though I knew that I got made fun of if I ever said anything about it, I still did it anyway. Bought all of the books, spend weekends over at my friends' houses and had epic sessions, and (at least as far as I knew) provided us all with a lot of fun.
That's why, when I see a young person who admits that their friends don't understand why they do (blank), I always tell them that if it makes them happy, keep doing it. I know plenty of people who turned doing what they love into a career of some kind. Don't ever let anyone else tell you what you can or can't do with your time. In the end, the only person whose opinion matters when it comes to things like that, is you. If it makes you happy, the naysayers can either accept it or they can fuck off, but they don't get to have a say in it :)