My observations over the years is that through training you can become very good and compete with the top of the Fleet
The champions have what has been called the winning edge.
That is they are about 3% better than the rest and that is something that can't be taught.
Tiger was mentioned. His scoring average is a very small percentage (3%)better than the guy that earned one tenth the money he did. This can be applied to many sports and in business.
The very old saying: "It's the nut on the end of the tiller" that makes all the differance is always true.
Like in Football, Baseball etc.. , you can't teach foot speed.
In sailing, I don't think you can teach the touch or the instinct that makes you that 3% better and ultimately a champion.
I have been lucky enough to sail against guys like Enrique Figueroa, Bob Curry, Hobie Jr, Randy Smyth and Carlton Tucker. All National and World Champions. They all started winning very early in their sailing carreers and kept it going for many years. They all have the "It" factor you can't teach.