For all its talk of new revenue streams, Facebook is still dangerously dependent on display ads. And there is a tension between attracting users and squeezing money out of them. Facebook’s greatest asset is the information that its users willingly surrender to it. Turning such data into cash, however, will inevitably raise privacy concerns. Most users don’t realise how much Facebook knows about them. If they start to feel that it is abusing their trust, they will clam up and log out.
Facebook: A fistful of dollars | The Economist