There are a lot of older people here, but the most active posters are the young ones. If you are here during the summer, thats when you really see a flood of kids.
A big reason is that most tend to drop PC gaming after high school graduation because they dont have the time nor money. It would be the same for me if I wasn't living with my parents. TF had a lot more adults before it was so gaming-oriented.
BTW, Im 20.