Facebook takes your information and sells it. Technological "soylent green". Don't know if this still works: but several years ago, before I closed the account I experimented. I put my location/address Ethiopia and later a couple of other third world countries. I began to get popup ads on web pages and emails from the Canadian and British health systems asking if I was a doctor or nurse. If I was, they would pay to immigrate me to Canadian or British to work national health systems.
The only way they could have come up with me as a potential immigration candidate was if they were getting information from Facebook. It also said a lot about how desperate the Canadian and British health systems were.