[tim333]

For Facebook current profits are about $6bn a year. To justify a 319bn cap they'd have to earn maybe $18bn /year giving a 18x PE, or about 3x what they do today. I think it's quite likely they'll achieve that in the next 5-10 years.

You've got remember the billions of rural poor will probably be less poor in a decade or two.

[microtherion]

That's quite plausible, but they have a $319B market cap today, so current shareholders would see their stock flatline over those 5-10 years.