No quantitative idea, but as disgusting as the salaries for football coaches (N.B., depending on the school, it may be a budget separate from the academic enterprise), university presidents, &c. are, I would be willing to bet that they are dwarfed by the army of bureaucrats handling what I termed regulatory compliance.
On the research side, off the top of my head you've got grant administrators, institute review boards, research integrity office, postdoc affairs. You've also got "Title IX administrators". Accepting federal funding takes a lot of work.
The worthiness of the services the bureaucrats are providing I leave as an exercise to the reader, but I think it's problematic that the people making the regulations are not the ones paying the bills when it comes time to comply with the regulations.