Gary Vaynerchuk in a 2012 keynote at Inbound said a bunch of good stuff, but this was most profound:

"I don't care about Facebook, Pinterest, tumblr, twitter. I care about social media because it sells shit! ... this is where I think the cash is going, where the customers are going! This is where the customers' attentions are going." This is where you have to be in order to tell your story!

The game in business is retention, how many customers you keep (20 min). Lifetime value of a customer is the best metric.