Well if you think Murdoch made a mistake it's not surprising you think Facebook investors would be making the same one.
The people who believed Google would monetize their business in a huge way seemed to do alright. I don't think Murdoch regrets his decision. I do think people should be cautious but you're going way beyond saying just that.
Well, although I think the mySpace deal is crazy, it's at least somewhat attainable. Murdoch has a bit of a history though of making bad moves in tech. He was nailed on Gemstar. Compared to the $11B he lost then, mySpace is peanuts.
The money being talked about though for Facebook and others cannot possibly be recovered though unless a number of stars align, and that's too much for me. ;-)
At 100 million visitors, $25M translates to $4 a month per user in ad funds. $4, per user, per month, sustained for 24 months. Just to break even.
Those are insane prices at insane growth trajectories. You can call that justification of a valuation, but I call it unsustainable speculation.