For the poor, it is a way out. Even if you don't hit the pro level, being good at football can get you a full ride scholarship to a great school.
One of my friends at Berkeley was in exactly this situation. He grew up very very poor, played football at the local high school, and managed to get a football scholarship to Berkeley. He wasn't very good at football, and rarely played at all, but he did get a full ride scholarship that covered tuition, housing, food, books, and a small stipend for living expenses. He also got a job working in the residence halls, which also came with free housing and food, so he basically made money in college.
Then he graduated with a PhD in Education. He could have never afforded that without football.