1. For most people and most degrees, college does not make one more useful to society.
2. Even for those people/degrees that do make people more useful, that doesn't mean society benefits from an unlimited number of them. For example, a math degree likely makes one more useful as a math teacher, but society does not have an unlimited need for math teachers.
We should stop encouraging people to go to college. It's a huge waste of societal resources, most particularly the years of life of the students themselves. How about go to work after high school, and then if you feel like you would benefit from additional formal education, then you go to college.