https://www.newyorker.com/magazine/2016/10/10/sam-altmans-ma...
and most importantly, from http://www.paulgraham.com/fundraising.html
'At YC we spend a lot of time trying to predict how the startups we've funded will do, because we're trying to learn how to pick winners. We've now watched the trajectories of so many startups that we're getting better at predicting them. And when we're talking about startups we think are likely to succeed, what we find ourselves saying is things like "Oh, those guys can take care of themselves. They'll be fine." Not "those guys are really smart" or "those guys are working on a great idea." [6] When we predict good outcomes for startups, the qualities that come up in the supporting arguments are toughness, adaptability, determination. Which means to the extent we're correct, those are the qualities you need to win. 'Investors know this, at least unconsciously. The reason they like it when you don't need them is not simply that they like what they can't have, but because that quality is what makes founders succeed. 'Sam Altman has it. You could parachute him into an island full of cannibals and come back in 5 years and he'd be the king. If you're Sam Altman, you don't have to be profitable to convey to investors that you'll succeed with or without them. (He wasn't, and he did.) Not everyone has Sam's deal-making ability. I myself don't. But if you don't, you can let the numbers speak for you.'
He is also from early batch of YC who co-incidently were very intimately connected with PG.
someone above said zuck was pretty much "luck" which I dont think is true. Even though you might hate him for a lot of things, he is pretty darn smart.
edit add "luck"
I think what a lot of us in the "luck" camp are trying to convey is: There are a lot of "pretty darn smart" people in tech. A LOT. Hundreds of thousands, who could be the next great startup CEO, could be a VP of engineering at BigTech, could lead the next technology team that disrupts $1T industries. They aren't because there are very few of these roles in the world, and only a few of the many "pretty darn smart" people can slot into them. How these roles get distributed among the many talented, brilliant people can only be described as random. For every brilliant, hard working, startup CEO you can point to, I can probably point to 1000 people who are equally brilliant and hard working, but simply didn't roll the dice a thousand times in the exact way the "successful startup CEO" did. The rest of these brilliant minds are often plugging away in obscurity as run-of-the-mill senior software engineers, purely based on the random walk their lives happened to take.