Check out this fascinating 13 min interview with Christopher Wylie, a former research director at Cambridge Analytica, who had a copy of a dataset with 50 million Facebook profiles. He ends off with: "I approach anything with a healthy dose of skepticism".... I would agree!
Wylie details how Cambridge Analytics came into existence and how it used those 50m profiles to create a culture-changing data machine. Social Engineering on a country-wide scale, politically weaponizing data. Very instructive, scary, and a short manual for bad guys how to do spear phishing at scale: https://youtu.be/FXdYSQ6nu-M
Cambridge Analytica just suspended CEO Alexander Nix amid this Facebook data scandal. More background at an article at The Register: