Williams can get that much and there's not a damn thing you can do to stop him from getting it.
Yeah, I get it, you're lumping in the signing bonus to make it look like a huge difference, and I did address it, by pointing out he's still going to get that signing bonus the following year and average NFL salary per year for the top pick is ~9 mil. It doesn't matter what age he plays to, QBs are playing for that 2nd big contract. And there is certainly no guarantee he'll ball out and earn the big 2nd contract so any more money he earns before coming to the NFL, is absolutely advantageous.