Student athletes are such a narrow subset of the overall population of a college, that using them as an example doesn't really make any kind of case about whether subsidies help or hurt.
Going to college doesn't ensure broad knowledge or a quality education, but it sure is a prerequisite to those things in this day and age. And we should try to give that opportunity to as many smart, motivated people as we can find in our country, irrespective of their ability to pay. The alternative is a return to deep class stratification. There's no guarantee that anyone will receive a quality education even at a quality school. Demanding that as a prerequisite to subsidies is like demanding that farmers not lose crops as a prerequisite to subsidizing corn.