I would expect that PG/EG participants in math competitions find themselves up against other PG/EG participants in short order, at which point the number hours of study and practice become a significant determining factor in success. Once "Who wants it more?" is a major part of the activity, it becomes very easy for someone to say, "Not me," or, "Eh... I want it, but not that badly."
Competitions can be fun and healthy, but striving for the very highest levels is often unhealthy. Training at any one thing comes with real opportunity costs as it crowds out other healthy activities, and the individual has to be willing to pay those costs.
