My point is not that there’s no young high level dressage riders anywhere ever. More that it takes an amazing amount of cash, and/or connections, and multiple horses, plus being in a region or country with a very strong support network for dressage and riding generally.
Other sports peak early. If you aren’t a top gymnast by 15 you are not going anywhere. Riding by contrast is not a youth sport.
At the moment, teen daughter (who is leggy and a good fit for him from the videos) would be doing amazingly well to get him trained with help of coach and up to say third or fourth level, which appears to be the maximum for this dressage program based on the videos. Or even second.
Then she’s going to be in college with a whole other set of concerns.
Learning good groundwork and rehab is a wonderful experience for a teen, most teens in a program skip this in favor of competition and miss elements of horsemanship.