content: Firstly, it is practically required as part of copyright law to surrender your content so that other companies that rely on user related content to host it.  Once theirs, they can do whatever they want with it.  Including all sorts of fun datamining. Secondly, it is incredibly easy to sign away privacy rights.  The legal "user agreements" will make 99% of people's eyes glaze over and they just click agree to get past it.  I remember reading somewhere that the average person would have to spend 2 months out of the year reading legal documents as a full time job just to properly have a chance at knowing what's behind all of those "I agree" buttons, but that's to say nothing of understanding those laws.