The potential sacrifices itself if you don't utilize it as you mature, and you just end up a 40 year old lost boy, which is a horrifying thing to behold. It's almost as if you're the living corpse of a child, because who wants a six year old 40-year-old? You're a little on the stale side by that point, and you're not the world's happiest individual. Your potential is going to disappear because you age anyways, so you might as well shape that potential in a particular direction and at least become something, no matter how limited, rather than nothing.