The make millions of dollars off unpaid labor, any person who makes tons of money (more than a professional often) expressly because the people doing the work don't have to be paid and has no problem with it cannot be anything but a deeply immoral person.
Even worse, coaches at major college teams in revenue generating sports know that this system is not only unfair, but corrupt. They know that when there is a large amount of money riding on the current and future performance of unpaid athletes, some of that money will find it's way to those athletes. But instead of enforcing the rules they are given or advocating for the payment of their athletes, they maintain the current sham of a system because they know that forcing the money under the table gives them a bigger cut. So they set up their processes so that there are assistant coaches as fall guys and plausible deniability for themselves. The control freaks who dictate every second of their player's lives on and off the court suddenly just don't know what is going on when an agent or booster is slipping a kid cash, or when recruits get plied with booze and strippers. They make a fortune, their ADs make a fortune, their schools make a fortune, and their athletes are left unpaid or underpaid, and usually either without a degree or with a sham degree in whatever major was easiest instead of useful. They are inherently scumbags.
(But I'm sure your favorite coach or the one at your favorite school are the exceptions that do it right.)