My initial thoughts on Zuckerberg was that he was technically brilliant. But maybe "The Social Network" gave me the wrong impression.
Anyway, Mark is smart, but so are a lot of people. And Chris was the marketing guy who got the site in the Crimson with impressive frequency, not Mark.
I have met both. Again, they are both smart, but many people are smart. Many people who read Hacker News are technically capable of doing what each of them has done. Of those, very few were also able to benefit from a number of the external forces that supported each of them, and fewer still would actually want to do what each of them did.
So while they both may be quite intelligent people, they are not the most intelligent people ever to have lived, and are probably not even close. Being "brilliant" and being rich are not the same and there is no causal link in either direction!