What evidence is there of this?
No real investment fund that gets it's money from legit investors would consistently overpay...i.e. they "valued" facebook at 10 billion...at a time when facebook had problems raising funds at even a lower valuation. Why would you overpay when you don't have to?
Also, as outsiders, it's impossible to know enough about what the exact funding situation for Facebook looked like at the time to make conclusions about overpaying.
That's a ridiculous statement. Like Facebook or not, they've attracted a world-class team, are growing increasingly fast, and have consistently innovated in ways the rest of the Valley hasn't seen coming. The announcements at f8 just a few days ago are a great example of this. Facebook may or may not become Google -- or even Microsoft -- sized, but their risk is almost entirely execution now (and they've continually proven they know how to execute).