If Facebook were to charge when they were smaller, it would have stopped growth and allowed a competitor to take most of their user base. I would not have paid anything when I first started using the service.
Not only do I think its a poor way of sharing information, its always had huge swings of spam-ridden News Feeds, and forced user adoptions in terms of UI, etc.
The thing is, what is important about a social network? the other people on the network. If you had a quality filter on that network, sure, I'd pay a buck.
Some people would even argue that the buck /is/ a quality filter... to some extent, it is, if you use that dollar to verify the identity of the user in question. (I mean, this is important more on professional networks, like linkedin) but yeah, in some contexts? that'd be great.
but, if you mean "can facebook make money from charging people a buck a year?" my guess is "probably not." - it would have to be a niche network.
Facebook is making $183 Million per year off mobile ads whilst, this may not be a huge number when considering Facebook's user numbers, the amount of users who use Facebook on their phone or even the amount of users who only use Facebook through their phone this number is certainly going to grow considerably over the next few years.
In fact, Facebook haven't even rolled out these advertisements worldwide yet and the ones they are testing are only showing every 150 or so, again this is something Facebook aren't being aggressive about their CFO David Ebersman said Facebook are "being very careful about the volume of sponsored stories in the news feed because it’s so core to the user experience."
But I still think people would rather start using something else. It would only give Google the opportunity to start advertising Google+ as the FREE social network on TV and elsewhere.
Meanwhile, CPC for Facebook ads is much higher than 2 cents - or I'd be spending a lot more money there. $.2 - $.4 is more common.
So assuming a FB user checks an average of 10 pages a day (which sounds about right, given, say, a few profile refreshes, a couple of message replies, a photo or two, maybe a game) that's 3000 page views approx over a year, which is 15000 ad views, giving us about 12 clicks at about $.3 each, for a customer value per year of closer to $4 or so.
Having said that, $5 per year still isn't very much to pay...
You just go to https://www.facebook.com/help/delete_account
And as somebody else mentioned, if Google wanted to charge $1/yr for all their services, I'd be glad to pay it. Same goes for iCloud and other Apple related services.