Speculation on the future. They have more data on you than anyone has had, ever. And, they are attracting the smartest people on earth. With those two things combined, they are going to be able to do a lot more than display Ads based on your listed interests and relationship status.

Think: modeling a marketing scheme against FB's data because they understand the idiosyncratic specifics of the demographic you are trying to hit, thus telling you with p<.01 whether or not it will be profitable.

That, and government contracts are profitable.