This seems far too deterministic and I think is contrary to what you're replying to.
It sounds more like a 99.999th percentile person[0] that constantly reaches too far too early, before being prepared, will not have a 99.999th percentile life. A 99th percentile person who, on the other hand, does not constantly fail due to over-reach, can easily end up accomplishing more. (And there are many other things that might hold them back too - they might get hit by a car while crossing the street.)
[0] in whatever measurement of "capability" you have in mind