What this thread really exposes is the typical good runner's athletic self-worth issues (which, not to play psychiatrist, probably stem from having stumbled upon running only after years of sucking at football, baseball, etc.):
I disagree. The football, baseball, lacrosse, hockey players in my school were all more gifted natural athletes than the track geeks. The "leftover" runners by and large all broke 5 minute miles and we did not have a strong high school coach.
What is a "natural athlete?" Our sense of what makes an athlete is defined by the sports our culture celebrates. In the US, where football, basketball, and baseball are the big three (for the purposes of this discussion, NASCAR isn't a sport), a "natural athlete" is someone who has good speed/quickness (fast-twitch muscles), excellent hand-eye coordination, good strength (high maximum muscular force), and high muscular power output. These genetic predispositions are mostly either irrelevant (hand-eye coordination) or detrimental (strength, speed, and power) for running a sub-5 mile. A natural runner and a natural football player are not the same thing. Soccer players are the exception in this regard since they are generally seen as "natural athletes," but also tend to make good mid-distance runners (especially midfielders).
That strength, speed, and power are detrimental may surprise some people, but remember that the mile is already getting pretty high up in distance as far as muscle fiber composition is concerned, and that it is run PRIMARILY (though certainly not entirely) off fast and slow oxidative (rather than fast glycolitic) muscle fibers. Someone who's a natural for speed/power/strengh sports probably has a primarily fast glycolitic muscle composition. A natural football player (linesman excepted) would generally be a much better sprinter than mid-distance runner (hence the football players who sprint in spring track).
All of that is to say that runners shouldn't let the insecurity they feel about not being able to average 5 yards per carry or hit .315 cloud their perception of how hard (or easy) it is to run a 5:00 mile. Sure, a 5:00 mile is nothing special, but:
a) not everyone is physiologically adapted to train 100mpw
b the reason poor runners often seem to be "unmotivated" is that they try serious training and either get injured or don't improve.
c) however many sub-5 guys there were or were not on your HS track team is irrelavant. We need to look at general trends, not annecdotal evidence. Anyone ever hear of small sample size?
d) there really are people who could train 100mpw and not break 5 in the mile.
e) (The only truly original point I'm making): There are many PHENOMENAL athletes who could never break five in the mile no matter how hard they trained. Human muscle composition means would be impossible for someone to have elite talent in both the 100m and the marathon. I don't know how many elite 60/100 guys could break five if for some strange reason they concentrated on it, but I'm not certain it would be all of them. Their primarily fast-glycolytic muscle composition would actually work against them.
I think W.Mitty (a James Thurber fan, cool) has been right on the money with his statistical work. A normal distribution study is absolutely the way to go. I'm prepared to believe that percentages would go up a bit if we managed to give everyone unflagging motivation and perfect training resources including unlimited time (question: are we theoretically protecting them all from injury and other training setbacks as well?), but I don't see the percentage going over 25.