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.
Yes, but for some competitive activities, the rewards are meager unless you are one of the very best. Chess is discussed often here. I would not advise someone to become a professional chess player unless they can become one of the top ten players in the world. "Burn out" in sports, chess, and other activities may be a rational response to the understanding that you are very good at X but that there are other people who are even better.
