Earlier quoted context omitted.
What if the reason people are 'smart' is because of the way their brain has organized itself over the years in response to learning so much? Then it isn't that dumb people are dumb, just behind.
That isn't reality. The genetic factors of intelligence are well documented. I could have played basketball six hours a day, every day for the last 25 years, and I'd be really really good. But I wouldn't be as good as Lebron James was when he was 12 years old.
If you want to be the best in the world, it's true that factors outside of your control come into play. If you can "settle" for being in the top 10, top 100, or top 1000, instead of #1, you probably don't need much besides a lot of well-directed effort.
In my experience.