The most important factor is speed and quickness. Many millions of people can do the same actions as the pros, but nowhere near as fast. The top players are among the fastest/quickest people on the planet. World class speed can be honed by training, but it cannot be created by training.

Of course, even those with the necessary raw athletic skills must train hard, and follow the career path necessary to be a pro. That career path varies depending upon where one lives.