On the one hand, Facebook is mired in the same relentless downward pressure of falling per-user revenues as the rest of Web-based media. The company makes a pitiful and shrinking $5 per customer per year, which puts it somewhat ahead of the Huffington Post and somewhat behind the New York Times' digital business. (Here's the heartbreaking truth about the difference between new media and old: even in the New York Times' declining traditional business, a subscriber is still worth more than $1,000 a year.)
That's a pretty amazing number. A big difference, of course, is that home delivery of the printed NY Times is much more expensive than any online option. (Full price is $800/year in Berkeley, though I'm sure you can get that discounted in many ways.)
Is the rest of the difference advertising? Why is advertising so much more valuable in the print edition? There are a lot of reasons. One I can think of is that the NY Times seems to get a lot of prestige advertising. It is, after all, the "newspaper of record." During the fall, the Sunday Arts section has a full-page ad for seemingly every movie that comes out. Every time a big corporation kills innocent people or wrecks the environment, there goto PR plan is to post an apology in the form of a full-page ad in the editorial section. It's hard to think of an online ad with similar gravitas.
The real problem with online advertising is that it's completely metrics/ROI driven, not a cultural institution.