They get paid what the establishment thinks they're worth.
Obviously a university is not going to pay their football coach $7 million if the program is only bringing in $6 million.
What happened to the idea that college sports is an amateur sport.? You're not addressing the issue.
The players have always been considered to be amateur, but the programs are into making as much money as possible and have been that way for longer than all of us here have been alive.