Well I definitely think it takes a combination of skill and natural ability. In the case of Pistol Pete, he's one of the ones who didn't need the full 10,000 hours to become an expert on shooting.
I think we might be underestimating 10,000 hours. For example, there are only 8,760 hours in a year. Plus we're not accounting for sleep, eating, school, church (for some), driving to all these places, etc.
I certainly agree that genes generally dictate how tall we are, how fast or strong we can become, how high we can jump, etc. But traits of skill do require practice. How much practice per individual? Now we're getting into the role of genetics.
I bet the Curry boys have shooting basketballs since they could stand. And they didn't have some random hobo teaching them, they had a great shooter of a father to teach them form and release.
Genetics vs training is far from being a "fact" though. I was a biology major in college and scientists are still studying which has the bigger impact on an athele's success (genes vs work).