Some quick back-of-the-envelope math for how much the co-founders walked away with. Assuming the first round of $500K was @ $2.5M valuation, giving those investors 20%. So the founders are left with 80%. Further assume the 2nd round of $7M @ $20M valuation, giving those investors 35%. So the founders are left with 45%. Further assume the 3rd round of $40M @ $500M valuation, giving those investors 8%. So the founders…
Why do you think the FB stock is likely to appreciate significantly in a few months? If you really believe this, I assume you've just invested a significant chunk of your net worth into FB stocks?
That will likely push up demand for the stock in the short-term, thereby the price.
Aside from that, we have never seen a service have 800M users and still growing at the rate that FB is growing and have the stickiness that it has. So there is no telling how big it can get - which is why the valuation is so high.
There is no doubt that over the long term, FB will figure out a way to print money. It's just a matter of time.