At what age is it better to learn to play chess? Maybe at 5 years old maybe at 10.
Basically the earlier kid starts to play chess the better, since young mind is more flexible and learns things faster.
However, I believe that it’s mostly matters not when you start playing chess, but how much time and effort you dedicated to that game. If you start playing at 6 you may become a grandmaster by 16 with right training and talent. If you started at 30 maybe you’ll be able to become a grandmaster by 40.