Claims for Facebook making billions seem exagerated to me.
Google makes billions by knowing what you are looking for and offering more relevant ads.
Now consider how much more Facebook does know about you and what it can offer for advertisers.
Does Facebook really know more? Google knows everything I'm looking for and what I like through the tons of websites I visit (thanks to google analytics). And if you use gmail and google maps, it also knows your friends and where you go to.