The same reason why I don't believe Facebook will ever reach real profitability - their primary audience is a bunch of poor, broke college students, not to mention ones who are generally anti-corporate.

What about when they grow up?

One analyst put it best: "Who the hell thought it was a good idea to try to monetize the space where someone publicly breaks up with their fiance?"

That's when they realise they can't be wasting time on social networking websites thanks to the wife and kids.