What if they just really enjoy it though Allpast? You can still train hard and keep going with a sport without expecting to win gold at the olympics. Sticking with a sport (or any other hobby) and working hard can lead to other things.
Activities like this can open unexpected doors and perhaps even generate unexpected income if you are prepared to stick with them and train to the highest standard possible for you. My friend applied to a very competitive programme to work at a USA summer camp. It was his sporting hobby that made him stand out and win a place.
My DS was offered four free swimming lessons in a private pool at a local school and he hated the first two very much, he cried and on the third week he refused to get into the pool. He's only three and he was hysterical so we didn't take him. We tried again the fourth week and the same thing happened. We didn't want to force him into the pool and the instructor agreed it was a bad idea.
That could have been the end of it but we wanted him to learn to swim, not for the Olympic gold I was imagining in my other post but because learning to swim and being able to do so confidently is a skill we think it's very important for him to have.
DH took him to the public pool several days in a row to build his confidence. It was better because they have a shallow pool for small children and some fun water feature things in it, so he could paddle and play and get used to being in the water. It also meant we could be in the water with him to deal with any tears before the lesson started, something we couldn't do at the other pool. It made all the difference.
When he gained his confidence they went in the deeper pool and DH swam with him. And after three days of doing this we booked a course of lessons, which was a risk if he refused to go as they cost £50, but this time he loved them. The instructor actually gets in the pool with the children and she took the time to chat to my son first so he felt confident with her as well as with the water. When he had his first lesson here (third in total) he was like a different child and this time he cried because it was time to get out of the water.
I will say I've never been any good at swimming, or had much interest in it, and I'm not supposed to be in the water because of problems with my ears. But if DS loves it and wants to carry on, to whatever standard, then I will do everything I can to try and make it happen. If he gets older and feels a different sport is for him I will encourage him in that, although as swimming is a potentially life-saving skill as well as a sport, I would like him to keep going and be a confident swimmer as that was the point of taking him in the first place, to learn an important skill, have fun and keep fit. If that turns into a hobby that can at least give him opportunities or extra income, even if not the Olympic gold, then that's a bonus.