of the first round from 2017 (and pretend this is your 2018 salary) and the first pick of the 3rd round for 2017 (I'll give you a hint, the first rounder wins).

knowing where i'm slotted today vs the unknown of tomorrow vs the possibility of injury

against the unknown possibility that i might increase my position (or decrease)

and the intangibles of: i like my teammates, i like my coaches, i like college, i'd like to try to win a NC, etc

make it a difficult formula to overcome making the leap today if they're simply looking at the math of it

and like i said - whatever they decide is fine by me

But you can only make decisions based on what you know today, taking into account potential for the unknowns. If Coney/Tillery talked to the same scouts who are writing these articles about them, they'd get feedback that if they continue with their trajectory they could move from 3rd to 1st round. At that point, I think the math speaks for itself (if the last pick in the first round in 2018 invested all his bonus, he would have about $10 million more than the first pick of the 2017 3rd round in 2050 doing the same thing using your compound interest formula, even without that extra year. And that's just the guaranteed bonus). But there's no guarantees either way, I agree with that.