That depends on whether Facebook can ever monetize their users to an extent great enough to generate the profits that would cover such a valuation. Right now i

That depends on whether Facebook can ever monetize their users to an extent great enough to generate the profits that would cover such a valuation. Right now it's not looking so good. There is only so much growth they're going to get in the west (which is where users are worth money) and growing elsewhere is more of a strain on resources than something that will generate revenue. Search advertising seems to monetize so much better than pretty much anything else on the web and that's why Google is sitting pretty. Advertising just doesn't seem to monetize enough on Facebook and the like and the average value of their users keeps going down as the purchasing power of a lot of their growth is small.* *That's not to say that poor people aren't wonderful, just less valuable to advertise to.