i think about this same thing way way way too often. i wish i could let it go, and sometimes think i should will it on myself to do that.
was in a similar range in HS and thought i'd be on track to sub 4:00. didn't quite happen in college due to a variety of factors. now at 30 myself i see guys putting up big numbers in their 30s and wonder why i couldn't do it myself. i beat my college PRs in my mid and late 20s with brief stints of training.
but i won't do it now if it takes away from other commitments in life. it's simply too much solo time spent on a single goal of my own. but if i could integrate it with other things in my life (coaching/training a HS team? part of a social running team?) i might consider it. but my guess is that a lot of guys get the itch, hammer away at it for a short burst, get hurt and don't want to deal with it.
best of luck to you.