Theres no doubt that it would be a profitable venture but Facebook is concerned about more than just profit and at the moment. I get the impression that revenue

Theres no doubt that it would be a profitable venture but Facebook is concerned about more than just profit and at the moment. I get the impression that revenue is not their primary concern or least they aren't focused on maximizing revenue at the moment. Instead they're tweaking their product and growing the userbase to try to position themselves to maximize revenues later and become a force in the business world to compete with the likes of Google, Apple, Microsoft etc.