As a big data analyst I can say that the data from Facebook barely scratches the surface that we can grab from your web, bank, and shop histories. I can tell the amount of spend you put on a particular bank card, stores you frequent, items you tend to buy on sale, brand loyalty, ect.
FB gets a bad rap for this but honestly they are more closed then a lot of people think. You have to cross a ton of hurdles to get data from them and it is not always the best unless the user actually likes something you have sponsored or on your companies page. We are able to get a LOT more info from your store discount cards you use or credit/debit cards. The amount of data out there on each one of us is truely astounding which is both awesome and scary at the same time.
People want the data to be used to aid their lives (lower prices on certain goods, offer coupons, discounts, reminders on in stock products, ect) but at the same time are upset when they realize we have their data. It is a dual edge sword.
Being online, using google, being on social networks, shopping with discount cards, using electronic payment, ect all leaves a rather hefty data trail. I have heard from friends before that they cut FB to limit their exposure and I guess that is true but as one in the data the FB data elements are perhaps the sprinkles on a 10 tier cake. The data points are nice to have but the core of the knowledge on the customer is already from other sources.