Congress wasn't ready to interview Zuckerberg, he EASILY outmaneuvered them without saying anything of substance.
I want to say that FB does sell information, not in the sense I can facebook Rob and buy your information but I have advertised for years on FB and they charge me to advertise after they give me information they have collected on all their users and the let me sort through a sincerely overwhelming amount of information.
If I want to market to certain incomes sorted, geography sorted, age, hobbies, gender, race..........they have so much data that if you want to you could market to only people that watch Rachel Maddow on msnbc and start to pick apart the demographics of that group.
Make no mistake FB is in the business of selling information, Congress should have started an ad campaign on FB to see how it works before they interviewed Zuckerberg.