Everyone uses social media differently, for personal, business or for entertainment use. But what value most to twitter is its users, and I believe there is no specific amount it cost. More important is, we are able to communicate, share and express our feelings through it.
It's not very likely that any of us will ever see that money. Also, just consider how much money it takes to host all those servers where the billions of tweets are kept. None of that is ever erased and lives on to infinity. The real question here is what happens to that information if Twitter ever goes out of business. Not a likely possibility, but anything can happen in the internet world. And if it does, would Twitter sell all that private info to the highest bidder? What's to stop them? Read the TOS of any social networking site and you'll quickly see how you relinquish possession of anything posted there publicly or privately.