I feel like the tone of the OP is that "These are just normal kids. They should just focus on getting an education."
They're not normal college kids, though. You know how many scholarships are available among the 69 "power" teams? 5,865. That means of the 1 million plus high school football players, ~.6% get high D1 scholarships.
These guys already the best of their age group, and they're treated like a commodity from the moment they hit middle school. (See the entire recruiting board for goodness sake.)
So why should their aim be a degree and then start at the bottom rung of some office job when their elite athletic ability could theoretically earn them much more much faster?