Don't agree with this at all.
There is plenty of people that put as much if not more effort in training than Messi did and they will never be good even to tie his boots.
He was born to play football and be the best at it.
Ronaldo for example has a very good work ethic, and at his absolute peek he was as good as Messi on his peek, not better not worse.
Good work ethics and dedication plays a part for sure, but there is other factors that you can't really change.
On the CS example you gave, IMO even if I started playing hours and hours I would't be as good as Flusha because he played for YEARS, and most of the pros come from older versions of the game and since young they get to play it and practice it.