Zuckerberg influenced people to hand over their personal data.

His team then enabled lots of people to become influencers. Those influencers influence their followers to buy products (aka generate ad-revenue).

And that is the pure essence of the business model.

I don't mean it in a "super bowl commercial" way; the products in Instagram ads are the consistently interesting part. It seems like a safe assumption that the advertisers for plenty of uninteresting products are trying to buy ads on Instagram, and that the advertisers for plenty of interesting products are trying to buy ads elsewhere. That means that Instagram's targeting is the differentiating factor.