Take olympic athletes. There are differences not only in the level of work but also physiologically between those who win gold medals and those who can't be olympic athletes. If you're a would-be gold medalist why isn't it possible to settle for getting into the olympics and have a job on the side?
That's an interesting analogy. If you can find recorded examples of part-time Olympic athletes from a competitive country that would help your point. By a competitive country, I mean one with non-negligible chance of getting a medal in that sport.
I wonder if they exist and if so, how rare.
I suspect it's extremely rare or non-existent for an athlete who holds another full-time job up to the selection time to get selected into a US Olympic swimming team, for example.
