Plus his 4 year guaranteed deal. He will also be 1 year closer to his 2nd contract. Not to mention the REAL endorsement dollars he will get as a NFL player.
If he came back to college he puts all of that at risk if he gets injured. 10, 15 or 20 million dollars of "NIL" money is chump change. And that's if you can even trust that you would get it. Any player in his situation would have to be monumentally stupid to even consider it.