Collegiate sports teams are not like other school-sponsored jobs. Student librarians cannot make millions of dollars if they plied their librarian skills on the open market. At least some college football players could. Student librarians don't face high risk of physical injury, disability, or long term health effects as part of their job. College football players do.
Pulling in 100m in revenue to supply 50 scholarships doesn't seem like the right tag line.
Also see below, most college sports revenue does not get pushed back into general academics.
Most alumni donations are to the university's athletic association - that's because those donations comes with the perks that alumni want - seats, being wined and dine, shaking the coach's hand, etc.
Talk of removing funding is absurd because its a system that's been this way for a long time - of course it would seem absurb to change it.