You need to watch The Scheme if you think there isn't much corruption going on. That movie was going to blast out during the NCAA tournament, and ended up getting lost in the wash of canceled sports and the pandemic.
The primary reason that you aren't seeing a lot of convictions is two-fold. First, at least one of the FBI people involved in the investigation turned up dirty himself, which made it somewhat problematic to prosecute.
Second, the "corruption" is not so much violations of the law as it is corruption of college athletics.
If I give a kid $100,000 to play hockey at UND, I don't think anyone has committed a crime. However, supposedly I have broken innumerable NCAA rules. NCAA rules are not laws. You don't go to jail for violating them, you get kicked out of NCAA sanctioned athletics.
So, when shoe companies funnel millions to kids, through coaches and handlers, it is a clear violation of whatever NCAA rules we think supposedly govern athletics, but it's less clear exactly what laws have been broken. Usually it has to do with a public employee (coach) soliciting or accepting bribes. But in those instances, the coaches themselves need to be profiting, I think.