Spending $13 million on a late first-rounder is fine for an NFL team because the risk you're taking is calculated—the players are somewhat known commodities by this point, as they all have a body of work that provides plenty of good data to assess their potential. Spending $13 million on a high school prospect is less a calculated risk and more of a crap shoot. Both investors (the NFL team, the NIL contributor) are clearly spending the money to build a better football team, but the NFL franchise can feel pretty good about the potential ROI whereas the NIL contributor is pretty much flying blind. Yeah, it's great that 20% of 4-stars in any cohort make the NFL, but that means 80% won't. Further, only around 6% of 4-stars in any cohort are selected in the first two rounds, which means 94% aren't. So the NIL contributor is spending that $13 million in the hopes that this one kid will be among that 6%, when it's far more likely he'll be among the other 94%.
If the NIL contributor was honest with him/herself and put together a decision tree to analyze the c/b of the situation, they'd logically conclude that the NIL money ceiling for an incoming 4-star prospect probably lies somewhere in the $500-750K range. $13 million is completely insane—it's simply a really, really bad investment.