It's not just that another 1.44 billion shares of Facebook will become available for sale between now and November. Or that Facebook, with its stock down 50 percent, remains one of the better-performing social media stocks.

A much bigger problem is confronting the social media world: It's called demographics.

At some point, the global economy will start growing again. When that happens, the guess here is that millions of unemployed and underplayed young people will find what has remained so elusive since 2008 -- jobs. Time then will suddenly become a precious commodity to them.

Based upon an anecdotal, unscientific survey I've conducted among twenty-somethings, their social media usage starts to tail off dramatically in their early twenties. That is precisely the juncture in their lives that just happens to coincide with landing one's first job and getting some spending power.

Some demographers have even predicted that by the end of this decade, the U.S. actually could face a shortage of workers. Outlandish though that may sound, stranger things have happened.

With 900 million users, Facebook seems to have a real business and simply needs to find a sound revenue model. Whether it can or can't is beyond me.

But many of the other social media companies are truly floundering. There is little doubt that the folks at Google are brainiacs, but they must be thanking their lucky stars that Groupon rejected their $6 billion offer.

Last week, The Wall Street Journal reported that Groupon salespeople are looking to bail as their bosses step up the pressure to "sell, sell, sell," creating an environment like the one at the penny-stock boiler room in the final days at Blinder & Robinson. Meanwhile Groupon's stock keeps tumbling and is 85 percent off its all-time high. If the economy really does get better, how generous are merchants going to remain when it comes to distributing coupons online?

Facebook shares are about two-thirds of the way to what Marketwatch contributor Mark Hulbert calculates to be their fair value of $13.80 at the time of the IPO. The one social media stock doing well is the one old folks like us use -- LinkedIn, which companies actually use to seek employees and adults use to communicate with fellow professionals.

But even among the success stories, funny things happen. Remember tech stars of the 1990s like Microsoft and Cisco? Their shares now sell at big discounts to public electric utilities and telecom companies. Who would have thunk it?