My youngest son was well on the way becoming an elite level cyclist (Utah state hill climb champion and time trial champion) and was even in discussions with semi-pro teams.
He sustained some type of chronic injury to his knee and dropped out of contention in racing.
He is still fast, but can only ride for about 90 min before he has to quit due to pain.

It has taken years, but he has come to realize that he loves cycling, and that competing was only a small part of that.
He is much healthier now mentally, having realized that. I think he is in a much better place even than when he was winning races.

It seems impossible to our children to accept that there is more to life than sports and competition, but there is. Finding something you love, and then just doing it because you love it, not just for the competition, is sustainable and a good place to be, imo.

But it sucks that external circumstances have derailed your son's efforts. I don't have an answer for that