Is it? Depends how you define smart but Zuck has consistently made unconventional moves, very young, that turned out to be wildly correct.
He started by limiting Facebook to colleges so it could scale.
He was able to attract top class engineering talent to help him.
He entered a crowded market and obliterated all his competitors entirely through having a superior social networking product.
He retained control over his own company - avoiding the kind of agist outing that Larry Page and Sergey Brin experienced (i.e. investors who demanded "adult supervision" in the form of Eric Schmidt).
He convinced Instagram to sell, and made it profitable, apparently.
He convinced WhatsApp to sell and probably will make it profitable.
How many people in the tech industry can point to such a track record at all, let alone at Zuck's age? The guy doesn't only seriously understand tech. He also understands people.