All great points. If someone has been an ultra elite freak all their life, then it doesn't matter. They can assume next year and be correct. But for the vast majority they need to cherish and take maximum advantage of that short peak window. Too many of them think late blooming status due to hard work is suddenly the equivalent of someone with that incredible raw ability.
They don't understand applied odds. That's another problem. When Jager stumbled over that last barrier he probably assumed he was favored to break 8 minutes multiple times the remainder of his career. Meanwhile the odds reset and don't particularly care about your one near miss. Odds don't change appreciably unless it's demonstrated numerous times, just like slow-creeping power ratings for a sports team.