2) A few comments say that people have a true love for the craft
I think there is a third element missing:
3) People who want to be at the helm of a big, enormous organization but don't give a darn about money.
Kinda like building your own cruise ship and race to the North Pole against other people who built their own ships
Also kinda like a politician creating their own political party and gathering consensus bit by bit up until one day it has 3/4th of the seats and the founder is elected President/Prime Minister
Zuckerberg is exactly this profile, he turned down so much money for FB in the early days, and kept turning down money up until he turned down spectacularly 1 Billion in cash. There was no way Zuck was gonna hand the helm of the ship to somebody else and be helicoptered back to mainland. He was determined to remain at the helm and reach the North Pole, which in fact, he did.
Same for Bill Gates, he only gave up the helm when the US Govt. threatned to essentially bomb and blow up Microsoft's ship.