The dichotomy you're implying is "that creepy uncle" on one hand and a large proportion of the population on the other, but it's the latter in both cases. The people between the ages of 14 and 80 are nearly the same number of people as the ones between 18 and 80, and the people between 14 and 17 don't have money to pay you during those years anyway.
Targeting them has a lower return than targeting people who are of age.
