[mmatants]

One thing to remember, too, is that the original Facebook was quite different from what we have today. It focused on personal profiles, and had features of almost like a dating site. A huge use case was organizing parties (I know that because that's what we did as a group of students). Newsfeed as a timewaster is a feature that evolved only later. Messages were clunky and a non-thing.

Any product that has persisted is actually a series of products sharing same name, but each targeting a different demographic - oftentimes even actually same set of people but at different life stages. And as sibling comments point out, it is all about just trying and trying (and also, it would seem, having super convenient access to millions of people to try things on).