During that time period FB’s growth was meteoric and unprecedented. That’s the only reason Google likely took so long as to launch when FB is at 800M users. Because at beginning of decade they were at half that. Go back to beginning of 2009 and they are close to a third from beginning of decade.

They weren’t small in terms of users. But they were small in that just a few years prior, their user amounts were a fraction of what they were during Google+‘s launch. With Friendster, Mysapce, and all the me too social networks losing, there was no way to know for sure Facebook would win out and last as a huge company in the early 00s.

In early 00s, their revenue and profits hadn’t caught up to user growth either. The mobile explosion hadn’t fully happened yet. As well as Instagram now being a key part of their growth and solid part of their revenue and profit.