‘In the world of growth hacking, users are a metric, not people. Every action a user took gave Facebook a better understanding of that user–and of that user’s friends–enabling the company to make tiny “improvements” in the user experience every day, which is to say it got better at manipulating the attention of users. Any advertiser could buy access to that attention. The Russians took full advantage.
Source: I Mentored Mark Zuckerberg. I Loved Facebook. But I Can’t Stay Silent About What’s Happening.