Someone who runs half your mileage or less could go breezing by you at mile 22. That person may not have trained as much as you did, but perhaps trained more optimally, running enough to elicit a training response from their body, but not enough to wipe it all out with the fatigue from overtraining. That is a possible pitfall from accumulating too much mileage. Some runners are simply more genetically gifted than others are, as well. The ability to run faster than someone else is predicated on a combination of God given ability, biomechanics, mental toughness, and proper training.
Mileage is only one part of that complicated equation.
In the end, we all manage to somehow work out a training schedule. How far we end up running is a mix of motivation, availability of time, physical health, and just plain love of being out there. If all of these factors combine to keep you on the road for mile after mile. I hope you enjoy it and reap the benefits. I'll probably only be doing eight.