For why?

Even describing social networking as a "product" is dodgy. Do they make money from the social networking? Nope - it's just a vehicle for advertising, that's all. And the advertising doesn't bring in any significant income anyway, compared to the income you could expect from investing that much money in any other business. This doesn't say how much money changed hands, but you can expect it's in the millions. If you invested that in a few clothes shops, or coffee shops, or damn near anything else, you'd be unlucky not to be getting a decent return on the investment within a year, and ongoing revenue year-on-year. Meantime Facebook *still* hasn't broken even, never mind ever turning a profit.