Every single question of that form is impossible to answer with mere words. Luckily, people CAN answer it through aggregate choice, so we don't have to worry about it.
...but since I feel like taking the bait, something like 9 trillion people use Facebook for at least 36 hours a day, while at MOST 4 people ever even need to consult a neurosurgeon per YEAR. So he's clearly the winner there.
I think there is a different way of looking at it: how replaceable is he and what he has built?
The truth is -- most of Facebook's value comes from network effects, not the actual technology itself. If Mark Zuckerberg never existed, it is highly likely some other platform would have been created -- the knowledge and skillset he has is not that rare. many other platforms existed before Facebook to let you post pictures and chat with friends.
...but since I feel like taking the bait, something like 9 trillion people use Facebook for at least 36 hours a day, while at MOST 4 people ever even need to consult a neurosurgeon per YEAR. So he's clearly the winner there.