I'm only 21, been D&Ding since I was 12 but only recently have been able to DM a serious campaign (meaning, 5 players and I know how to actually play). Never have I run a campaign that lasted more than a few sessions but this was always because of players not myself. I expect my current game to go MAYBE a year if I'm lucky.
What I want to know is where are the players (or DMs) who play 2+ year campaigns meeting (online - preferably VT) at least once every two weeks? Contact me because I would live that sort of devotion to a campaign.
So put me down for long campaigns, even though I've never been in one, it's always been my dream.
Honestly dude, you're not alone in this. I think probably, your closer to the norm than anything. And really, when you think about it, it's not that hard to figure out.
14-18 years old - High school. Well, supposing you manage to get a group together at 14, then, if you make the jump from junior high to high school, your friends move apart and your group fragments. And, let's face it, between school, part time jobs, girlfriends, and a HUGE amount of other things you could be doing, it's not easy to get 5 or 6 people in the same room at the same time weekly, let alone consistently for two years. Life is pretty topsy turvy.
19-23 (ish) - college age. Again, people move around and go off to school. Maybe you go away to school yourself. So, you've got this honking big break in the summer where half your group is all over the place and when you come back in the next year, who knows if your schedules match up again.
24-30+ - work, moving, getting married, kids. gaming takes a pretty serious beating here.
So, really dude, I don't think you're an outlier at all. It's us old fogies that grew up gaming before the Internet and Playstation 3 and Skyrim that have managed to have these longer term games. For someone your age right now? Yeah, I can see that being really, really tough.
Back when I was gaming in uni, campaigns lasted about 8 months because that's when school let out.