The fact that there is more money for marathons has little or nothing to do with the age/performance curve. Correlation does not equal causation. All track and field is financially challenged. The marathon is a special event. And it so happens that marathoners can slow the aging curve because endurance is so important. So yes it is an event that attracts athletes from shorter distances as they age because they still have the possibility of elite performance.
The fact remains that the shorter distances are dominated by younger runners. Pointing out outliers does not change that. The oldest 100 meter gold medalist ever was age 32. There is no reason to think someone like Hurts is elite. So on average he should age like everyone else. And there is probably a 75% chance that injuries will take a toll on his speed by his early 30s. Good speed might become average speed. Now if he has become above average at other parts of the game then he might age very well in his 30s, but to claim he has a great chance of losing little speed is just ignorance. Michael Vick missed 3 years of potential injury and even his early 30s were an example of declining speed. Russell Wilson is probably a better comp for Hurts. He was down to less than 200 yards rushing last year. Still effective, but can Hurts do the other things Wilson does when he is 33? Hard to tell.
Edit - I called your argument silly, not you. Apologize if that offends you. I'll just stick to flat out wrong and non-sensical for the arguments.