Did you remember Gold in the ancient times and Oil in the 90s? Data is the equivalent of these commodities currently allowing to earn revenue and make interest. If you do not know, our data is everywhere and everyone wants to own a pie of your data so they can make money of it.
Facebook is to me, more of a marketing platform than a social media platform. On the surface, it is all about posting, liking and sharing but Facebook, asides their stock price makes money internally and this is via advertising. In the past, peoplewould advertise on a page of the news paper but this means wasn't efficient as it had to do with random people buying the newspaper and the information might get to the wrong set of people with little or no interest but with facebook advertising, you will be targeting the right people as facebook solve the wrong people problem with the data and information shared on the platform.
A lot of people have complained about big firms having access to data of users but they still share this data with the same big firm. Apple, Google, Microsoft, Amazon and so on have a lot of access to data they it is sure that this companies will be fighting over who should have more data and who shouldn't. Apple on one end is working on some privacy update which would affect Facebook, it will allow its users know when facebook is about to do an upgrade and it will notify users if they want to allow facebook have access to their data continiously. Actually, the upgrade isn't attacking Facebook directly, but atleast this is what they would want you to see.
Although, a lot of people are against their data being harnessed by these companies, will they still click on no when asked id they want to share their data with the site?