Yet another gold rush claim

Microsoft are investing $240 million in Facebook at a staggering $15 billion valuation.

Facebook claim almost 50 million users. Thus each user is costing Microsoft a bit under $5, and is valued at $300.

I never watch ads on Facebook, and never spend money with my account there. Why that would be worth $300 to Facebook, Microsoft, and other investors is worse than false. There is no adherence to fact, no correspondence to potential profit.