I know this is an unpopular sentiment on this site, but the problem is that everything has at least some genetic component. In the extreme case, rats share about 95% of their DNA with humans but are incapable of doing any of our jobs or even living a decade. Even amongst humans, large differences exist: short people can never become NBA centers, 200cm people can never be great gymnasts, someone with Down's syndrome isn't going to make it as a physicist.
One heart breaking example I witnessed personally was a family member. He wanted more than anything to be a classical musician. From the age of four, he was taught by the same teacher who trained a very successful NY Philharmonic pianist (opera coach). He practiced many hours a day all through his school years and earned both undergraduate and graduate degrees in clarinet performance. By any objective measure he was a very good clarinetist. But he wasn't good enough to make a real living at it. Unlike his mother, who had perfect pitch by the end of grade school, he never developed it. He saw more than one talented peer surpass him in despite his extreme work ethic. In the end, after putting over 25 years of his life and his passion into it, he finally gave up on his dream and became a programmer. Unlike his experiences in music, he very quickly rose to the top of development groups and it was he who was the one surpassing others who had been working at it longer and harder.
Talent matters. There probably haven't been any specific genes linked with business ability as there have been with musical or leaping abilities, but it would be naive to assume that everyone can win if only they sacrifice enough. In many marginal cases, I'm sure effort would make the difference. In other cases, it would just be robbing oneself of valuable time that could be better spent on another pursuit.