> I don't think it's true at all. Considering it only takes 2 to 3 years to rack up the 10,000 hours to "master" something, young people can get very good at a lot of things.

They can, if they practice with feedback 8 hours a day.

Typically, young people, as a group, are not famous for practicing something 8 hours a day.

This means, for the group as a whole, it is true.