I believe the number of hours required to become an expert depends on both the nature of the field and the competition in it. Although there are a lot of table

I believe the number of hours required to become an expert depends on both the nature of the field and the competition in it. Although there are a lot of table tennis players in Britain, probably not too many devote significant effort and time to master it. Thus, the effort required to be in the top echelon is not that great. The same cannot be said for, say, American Football in the US or soccer in many countries. The 500 hours or so he spent on table tennis is woefully inadequate to master mathematics as well, but for a different reason. (Mastering math requires knowledge and skills on a huge amount of materials accumulated over centuries.)