"I think $80 bn valuation (or $70 as it is now) is way too inflated for the kind of revenues Facebook is making, and I think some of the investors are realizing

"I think $80 bn valuation (or $70 as it is now) is way too inflated for the kind of revenues Facebook is making, and I think some of the investors are realizing this and are starting to cash out now before all the others figure it out." What makes you think that?