Every wannabe media mogul has had this fantasy. You’ve won the lottery of lotteries and now have a cool $15 billion ($15,000,000,000) sitting in your bank account. So what media company would you buy?

That money could empower you to out-Murdoch Rupert, giving you more than a 25 percent ownership stake in his $55 billion News Corp. (NYSE: NWS) I can hear many of you -- especially those infected with the virulent new Web 2.0 virus -- muttering under your breath, But why would I want to be Rupert Murdoch? Yes, for today’s aspiring digital mogul, the ultimate fantasy is running a hot social network rather than a crusty old media empire.

So what could you buy with your new fortune? For $15 billion -- yes, just $15 billion -- you can buy an entire social networking site. What you would get for all those billions is an incredibly cool four-year-old Silicon Valley startup run by a 24-year-old programmer -- a Bill Gates 2.0, college drop-out so authentic that he barely possesses any verbal skills, business training, or leadership experience. Yeah, it’s such a cool company that it not only hasn’t figured out how to make money when it grows up, but doesn’t seem too bothered about becoming profitable in the short term either.

You can wake up now. Yes, open your eyes -- I’m afraid that the lottery of lotteries has already been won by a lucky contestant. And our once-in-a-business-cycle winner in Silicon Valley’s latest Ultimate Sweepstake is Mark Zuckerberg, the 24-year-old founder and CEO of Facebook . Last October, Microsoft Corp. (Nasdaq: MSFT) invested $240 million in a Series C round in exchange for 1.6 percent (yes, that’s one point six percent) ownership stake in the privately owned Facebook.

Even in today’s irrationally exuberant Web 2.0 economy, how is it possible that a 450-person startup without a coherent business model or an experienced management team should be worth the annual GDP of a real country like Jordan ($16 billion in 2007) or Bosnia ($14 billion in 2007)?

The Facebook valuation is, quite simply, absurd. We’ve seen this kind of madness before, of course, in the crazed exuberance of the Web 1.0 boom, when -- most ludicrously of all -- AOL Inc. (NYSE: AOL) backed itself into Time Warner Inc. (NYSE: TWX). But this is history repeating itself as farce -- the second coming of Netscape, Excite, Yahoo Inc. (Nasdaq: YHOO) and all the other “can’t-miss home run platforms” of the late 90s.

It can be partly explained by Microsoft’s paranoid attempt to keep Facebook out of Google’s hands. But such an inflated valuation is also about the race to own the digital future.  Facebook is seen by its investors to be more than just a platform play -- Facebook’s backers are betting on the social network being the new media platform. The Internet will get sucked up by Facebook and its viral eco-system of apps and widgets. Facebook will become a cleaner, better lit version of the Internet. And then, of course, it will be worth more -- much much more than just $15 billion.

That’s all in the long-term. But as economist John Maynard Keynes said, in the long term we are all dead. In the short term, before it colonizes the entire Internet, Facebook needs to prove that it’s a viable business by becoming accomplished in all that boring blocking and tackling craft of a real media company. It needs to show that it can translate its 38 million monthly eyeballs (last month at least) into revenue. It needs to demonstrate that it can build advertising into its community without spooking the loyalty of its members.

My guess is that Facebook will fail and, like a dodgy Wikipedia entry, be over-written by Silicon Valley’s next big thing. And Zuckerberg will be remembered/forgotten as that poor kid who won the lottery of lotteries and then mislaid his ticket on his way to the bank. But maybe that’s just my own nasty little fantasy.

— Andrew Keen, Silicon Valley author, broadcaster, and entrepreneur