Facebook made the transition to mobile faster than other competitors and successfully kept G+ from becoming competition.
The instagram purchase felt insane at the time ($1b to share photos) but facebook was able to convert it into a moneymaking juggernaut in time for the flattened growth of their flagship application.
Zuck hired Sheryl Sandburg and successfully turned a website with a ton of users into an ad-revenue machine. Plenty of other companies struggled to convert large user bases into dollars.
This obviously wasn't all based on him. He had other people around him working on this stuff and it isn't right to attribute all company success to the CEO. The metaverse play was obviously a legendary bust. But "he just got lucky" feels more like Myspace Tom than Zuckerberg in my mind.