There's also the fact that a rise in hyper individuality (especially in America) and predatory capitalism leads to a marked rise of self centeredness and narcissism in the population.

You have to protect yourself from people like that as they are emotional vampires who will suck you dry.

Maybe it's so prevalent amongst Millennials because of where they are in life and what's going on in the world at large. The more stress one is under the less bandwidth you have to deal with all fallout from troubled family, friends, and coworkers who just can't get it together or just don't want to. At some point, you have to prioritize.

The fact that it's become so wide spread amongst Millennials is as much or more a poor reflection on the rest of us than it is on them, whichever side you take.