Do you have any evidence of that at all? I would find that shocking. I really don't think it's happening. Few athletic department are even self-sufficient. It would be unfathomable to think that any are using athletic department revenue to fund the rest of the university.
Anyway... yes, the salaries should be increased. It is difficult for the B1G schools that sponsor more sports to compete on things like the salaries of assistant coaches. They need to find a way though.