Take violinists, for example. Essentially every single world renowned soloist was "some sort" of child prodigy. Now, I've heard some soloists argue that they were not, in fact, child prodigies. For example, may favorite violinist, Hilary Hahn, has said this. She still debuted with the Baltimore Symphony Orchestra when she was 12, and here she is performing as a soloist at 15: https://youtu.be/upkP46nvqVI. Nathan Milstein, one of the greatest violinists of all time, said he was "not very good until his teens" - he still started playing at the age of 5, and at the age of 11 Leopold Auer, a great violin teacher, invited him to become one of his students, so he clearly saw his potential.
I have no doubt lots of prodigies burn out. But, at least in the world of violins, essentially every great soloist was playing at an extremely high level by the time they were in middle school.
I had a friend who could play all the Chopin Etudes at age 9. Some of the best art simply requires a virtuoso to bring it to life.
It just takes many years worth of practice to get from being good by 7 years old standards to being good enough that people buy tickets to see your performance, especially in the classical music culture where skill, or "virtuoso", is everything.