Harriet Zuckerman, a sociologist, was investigating the roots of scientists who do top-class work leading to breakthroughs and discoveries.
After researching and digging in, the answer she came to was that the scientists who did the most groundbreaking work were not necessarily smarter or harder working, but rather built up an "accumulation of advantages."
By getting slightly ahead earlier in their careers, they'd get more opportunities to make interesting connections, present at events and conferences, get onto interesting research projects, connect with luminaries, find mentors, receive funding and grants, etc.
Any one of those, in isolation, wouldn't make the difference. But over 20 years, the gradual accumulation of advantages put them into places where they had the skills, connections, mental models, resources, credibility, etc, etc, to be working on the right problems with the right people and the right resources/tools at their disposal. And so they'd do breakthrough work.
If you buy the hypothesis, it suggests that it's not any one major point that leads to breakthroughs -- it's about gradually accumulating important, relatively small advantages, and watching them stack up and work as multipliers for you.