We didn't know that Facebook was compiling dossiers on every human being on the planet, even the ones without Facebook accounts.
https://www.propublica.org/article/its-complicated-facebooks...
They started recommending my friends from my high school. I went to a magnet school for my junior and senior years, and Facebook even recognized that. I graduated 10 years before I signed up. And the one piece I made sure I faked was the school I went to. I'm shy. If I wanted to communicate with someone I figured I'd add them myself.
Nothing magical to it. They had some other piece of data from someone else (or me from some other source) that matched up (the data was fake, but I had used it previously; I don't make that mistake anymore). But it showed me just how dedicated to getting all of this data they were.
I would even say it was against social norms. Don't talk to strangers. Don't give away your phone number. Don't give away your address. Don't tell state your mother's maiden name.
It was such a simple thing to get all of those new people on social media to give up all of that very personal information without hesitation. Yet, if some random person at the supermarket asked you any of those questions in person you'd definitely raise an eyebrow and walk away. SocialEngineering++