People who have been successful through out history (at least modern history) have been so because of the enormous effort they have put into their success, so argues Gladwell. He suggests that coming from a wealthy background and being born with a high IQ can help lay a foundation for that success but notes that there are more that many people who inherited wealth squander it and that there are more geniuses who have less than noteworthy jobs than those who do. Instead, proficiency and success usually comes after about seizing an opportunity, applying about 10,000 hours of practice and recognizing your cultural legacy. As with Gladwell's other books, Outliers presents a narrative with a broad collection of story to illustrate his point.
Interesting tidbit: nineteenth century European farmers generally worked about 1200 hours a year. That is 200 more hours a year than hunter/gatherers (and I was always under the impression that we changed from hunter/gatherer to farmer because it was easier). Both of these pale in comparison to the rice farmers of the era who generally worked (and many still do) 3000 hours a year.