It's just gathering up open source intel (OSINT) and looking for patterns and trends. This is just something human analysts do every day but at a much greater speed. It's all Open Source Info (public posts) on a media designed to put your life out to the world (Facebook / ect..). A crafty set of programmers with lots of time on their hands could do this, chances are some of them already have. This is just the machine equivalent of hiring 10,000+ Intel analysts.
I'm not a facebooker, I don't go near social media due to the massive security risk your taking by doing so. If I was on some sort of social media system, It would seem to be wise to restrict the whole damn thing to only show things to people I would manually set. No 1,000+ friends lists seeing everything about my life.