Don't forget, those teenagers entire families are now on Facebook. I concede that the actions of teenagers might be an indicator of what's to come, but the world has hardly 'moved on' yet.
"one country" that has a high GDP per capita, sweet-spot demographics for advertisers, and a high ad spend budget by marketers, that allows FB to generate considerable revenues. this is not just a "warning sign".
I'm gonna have to disagree with you on that one. Basically all social events are organised on Facebook with my friends because of how simple it is to do so and everyone uses it, general purpose chatting is also done on facebook to save credit