Facebook makes money. They seem to have roughly the attitude that Google did around 2000. I.e. they're making some money, could make more if that was their main focus, but their main focus in the short term is to evolve the site.

Not to say that FB is going to be as big as Google. Outliers on that scale may only appear every couple decades. But they have a similar hackerly vibe.

Let's do an interesting exercise. Facebook has 100 million users. Let's suppose 10% of that user base would be willing to pay a $1.99 to have a premium account (like unlimited number of photo albuns, customizable look&feel etc). That would mean almost $20m dollars monthly revenue, much much larger than their burn-rate. College students don't pay for SMS? Why some of them wouldn't then pay this small amount to Facebook? Sure, this is a very rough estimation based on old subscription-based business model. A product in a free market operates much differently than if you charge US$ $.01. But it only shows that Facebook has many ways to become successfully profitable. They are only being cautious.