In his book Discrimination and Disparities (2019), economist Thomas Sowell presents a theory of success.

It's all about "prerequisites and probabilities".

Out of five prerequisites for success in something, many people will have two or three of them, and a lot will have four. But only about one in eight will have all five. That sounds good, but means that the chance of failure is seven out of eight i.e. high.

There may be millions of golfers who are superb at one skill, such as driving off the tee, or putting, but professionals need to have a suite of skills much higher than the norm, plus greater than usual tenacity and ambition. 

Most pro golfers never win a major championship, yet just three (Arnold Palmer, Jack Nicklaus, and Tiger Woods) have won 200 among them. Most tennis players never win a Grand Slam, but Roger Federer, Rafael Nadal, and Novak Djokovic have won 20 each.

Both on the left and right of politics, Sowell says, people assume levels of success probability that are not realistic. They assume that if you remove social barriers like racism and poverty, people will finally get the opportunity to succeed.

But just taking obstacles away is never quite enough. There has to have been expertise, skills, networks already in place for a group or person to succeed.

For centuries, European Jews had to live in ghettos and were restricted to certain jobs like garment making or moneylending; their opportunities were severely limited. After universities began to admit Jews, there was an explosion in their influence in many areas of work.

This was not just because Jews were suddenly "educated". They had been part of a literate culture for a very long time. Rather, they just needed one more prerequisite - formal education qualifications, which provides acceptance into the higher tiers of society - to capitalize.

For groups as for individuals, success means having "all one's ducks lining up in a row". One duck missing, and nothing great happens. When they all suddenly line up, big things happen.