There are four kinds of runners (according to coach Jack Daniels):
1. Genetically endowed, high motivation. They train well, perform well, and often have fast times with rather low effort level. The "rabbits".
2. Genetically endowed, low motivation. These could be winners but don't train well, and often frustrate the coach.
3. Not genetically endowed, high motivation. These are the "Binghams", and are really who this thread is about. They may train seriously but still have low performance compared to group 1. Their effort level can be phenomenal because they are fighting a basic lack of ability.
4. Not genetically endowed, low motivation. Takes part in few or no events; does not enjoy them. (Most of the public is in this group).
So we see that there are basically two groups running these events, nos. 1 and 3 (they do grade into each other somewhat).
Personally I commend anyone who is not genetically endowed to have the gumption and personality to get out there and do what it takes to finish some of these grueling events.
PS for this reason I don't like the word "race". Participants in fair races should be fairly equal in ability, not genetic opposites.