Why is there only one Elon Musk? Why is there so much low-hanging fruit?

Even with the disclaimer that the variables are all probably correlated, I think the author is vastly vastly underestimating how strongly correlated these variables are going to be. Raw mental power and creativity + long-term planning and vision-making have a lot of overlap. Energy and persistence could basically be the same thing. Risk and pain tolerance is already captured by energy, persistence, ambition. These seem to boil down to about 2 variables. Ambition to do big things, capability (intellectual/physical/creative) to do big things. It's also missing a huge variable (which is part of capability) in resource availability. Doesn't matter how many of those characteristics you have if you're born in a war torn region in syria and don't have the opportunity to get out. You could still successfully pull yourself out of the situation and create a better life for yourself, which could be more difficult than building a rocket to go to mars, but the point is you won't be building the rocket, you'll be using your time figuring out how to escape.

With those 2-3 aspects, I think you'll find that there are a few thousand or tens of thousands of people at that level, which lines up with what we see. There's more than one billionaire (and people like Einstein revolutionized plenty without ending up on Forbes richest list). Throw in a bit of pure luck for good measure (really helps to have a tech bubble going full speed at the start of your career to get you the capital you need for later life, and on the flip side I'm sure SpaceX wasn't any easier to run when the 3rd rocket launch failed because of a really dumb little error that was nearly enough to destroy the company).