If you study marketing or advertising in general you will learn that data is vital for their targeting. I suggest some of you guys read the filter bubble. Every time someone uses a "free" app or game related to or not to Facebook you give up rights to use it.
For example,
you download FB on your phone. In return you get to use the app but you give up tons of your data to use the messenger app. That data can many times also be requested by 3rd party apps or games. Those apps may not have highly secure data centers as opposed to FB. Even if they did, data is being sold all over the world for fractions of cents for each persons records. Probably not the best case but regardless if your info is online just assume it's being sold unless you use highly secure stuff. Which there probably is ways like vpn's not being signed into facebook or google etc. while browsing the web.
Anyhow, it is a good reminder of why privacy crypto is the future. At least that little buckets of information won't be tracked or sold on the market like credit card transactions are at the moment to other credit card vendors. Just look at the opt in or opt out forms you get when getting a credit card. You can only opt out of so much...
FB screwed up pretty bad.