Narcissism much?
Social media, while useful for the rapid distribution of information, also serves as a vehicle for a sense of self-importance to those who feel that people really care what they ate, what they did, and who they don't like. Too often this rapid sharing of information causes issues though. Several things come to mind. First, you can't tell tone or intent via text. My own kids will say "can you believe what so and so said?". Almost always it's something that can be taken several different ways...usually the worst is assumed. Second, most people would NEVER say things to peoples face that they'll write in a text, email, blog, or other methods that don't involve actually seeing someone. And third, once sent/posted/tweeted, many of those comments that seemed appropriate to that mood at that one particular moment, can't easily be retracted.
The comedy of the Gen-Y's is they don't see that they're often losing the ability to communicate face to face, and they share details of their lives online that perhaps they'd never do in person and as with most things online, controlling information once "out there" is very difficult. They'll get it eventually, hopefully before they do or say something they'll regret years later.
