People seem to think that there is a one to one relationship with the data Facebook has concerning what you personally have uploaded or viewed or liked/disliked and the data that Facebook has about you. There isn’t.
First, it also has whatever anyone else has posted about you, whether you know they did or not.
Then they have public data. You had to give a name/address and with that data FB can track where you have lived, perhaps where you went to school, how expensive and how old your house and car is at least via tax value, many times you can get who the-immediate family is and more.
The real gold mines are other companies databases. Everyone buys and cross checks people against as many databases as they can. Stores, service companies and Credit Card companies all have and sell data about you. And Facebook does the same. It buys their data, combines it with their own, and resells it. Banks don’t give out personal information but they will sell your credit score. Same with Credit Cards from stores, and they WILL sell data on what you purchase with other companies.
Just because you didn’t post it doesn’t mean it isn’t there.