So, if Facebook is going to have between $400 million and $550 million revenue this year, does that put to rest once and for all the idea that they are unable to monetize their users?
Facebook's overhead certainly appears to be quite substantial. They are literally building new datacenters and are running a ton of equipment. Even if you could theoretically fire all the sales, marketing and HR types, you'd still be left with a pretty big bill at the end of each month.
Various online sources say that Facebook has a little over 1,000 employees. Let's say the average employee is $80K fully loaded. That's $80M/year just in payroll. You haven't even talked about real-estate to sit those employees in, PCs for them to work on, or the servers and infrastructure to run the company.
Also, much of that revenue (for all practical purposes, maybe all of it) seems to be advertising related. There is a lot of talk about the declining values of online advertising, and no one seems to have cracked the system on how to do that advertising in a fully effective manner. So, Facebooks revenue is coming from a source that they don't have a strong ability to manage and control (vs., say, user subscription fees).