You've been to the Olympics? Congratulations, and if holding back your mileage in high school was part of how you did that you make a good point. But Jim Ryun, Gerry Lindgren, and Cathy O'Brien also made it to the Olympics and obviously did not hold back their high school mileage. No offense, but without knowing who you are I think I'd rather have Lindgren's or Ryun's careers than yours but I can't be certain. On the other hand, Shorter certainly did keep his mileage low until he was out of college and I might take his career over anyone's so that's a point for you. Really, when you're talking about people who actually make an Olympic team you can find various things they did and didn't do while getting there. Jack Foster got to a couple Olympics and didn't even start running until he was 32. It's really too small a population to draw much in the line of conclusions from.
But here are a couple disagreements I have with you. One is the analogy to horses. Yes, a rider can drive a horse to run until it dies. That's a one off thing though, i.e, an exceptionally brutal experience. The closest human analogy might be people who die during marathons on hot days. On their own, horses will run until they don't want to run anymore and then stop until they want to run again. If they needed humans to rein them in they'd have died out in the wild and there wouldn't be any horses anymore. The human analogy here might be a coach or parent who drives a kid to keep running when the kid clearly has had enough and as part of an ongoing experience as opposed to one particular session. Yes, there are some people, kids included, who do self destructive things and some of them find their way into running. Those people probably need a coach to hold them back but that doesn't mean everyone who wants to run lot of miles is self destructive or needs someone to hold them back.
And while I agree with you that I'd rather make an Olympic team at 24, or really at any age, than run a sub 4:00 mile in high school, I will also say that you can defer too much of the present to the future. We can look at Lindgren's career and say that if he hadn't run so much in high school and made the '64 Olympic team he might have made the teams in '68, and '72, maybe even in '76 when he'd still have been just thirty or even in '84 when he'd only have been a year older than Lopes was. Or we could say that by '68 and beyond life could have taken him in a different direction and he'd never have made any Olympic team, never won any major international races or held a world record. There is an argument to be made for seizing the moment. Every accomplishment becomes a past accomplishment very quickly and there's no guarantee at all that deferring an accomplishment now will bring a greater one later on. At 66, I'd love to have a sub 4:00 mile in my past and I wouldn't care at this stage when I did it. If I had the chance of a sure 3:59 in high school I'd be as happy with it as if I'd done it in college or later and would not have traded it for a potential 3:55 later on.