In Facebook case it is even worse, FB is making money with you activities (login, from where, your connections, your likes, and also your posts).

They are profiling you heavily, even collecting data outside of FB.

And as a user you get paid with ads.... ads, more ads and even more ads... or FB is selling your profile.

Other platforms are doing this as well, but FB is really the worst. IMO even worse than the NSA.