Trend, not reason

I think Joshua has picked up on the trend, but the reasons may not be complete or arranged in order of importance. 
http://www.becomingminimalist.com/millennials/
All this comes back to Maslow's needs.

Overpopulation and Economy

The world is becoming severely overpopulated. Up until now, in Canada, we have experienced mainly localized overpopulation, as evidenced by the migration and ghost towns. We are now experiencing much broader overpopulation. Lock at the Indian reserves, and local working poor communities and areas of the cities. To be considered working, you need to be working or drawing EI. But what about all those who do bits of contract work. No clear record of how many. And the drug dealers supply chains. There are not the legal jobs around as there was when I was young. We important products, and thereby provide very low paying jobs offshore. Oh well. Our millennials behaviors are the result of economy first, population growth and resulting need to cut back economically. That is not a bad thing; there philosophy is the result. Crowding and economy are physical and beyond our control, but our survival must occur before any thing else matters.

Philosophy is Secondary

When one sits back and reads the Stoics and Buddhist literature/philosophy, I am struck by the similarity yet it becomes obvious that each was built on very different background cultural layers. What was taught was what was missing out of there societies, and on that existing foundation became a very peaceful and patience sage, buddha, or what ever. If we were to compare the sage to buddha, we would find little difference except in the internal reasons for doing. It is the background that any population is raised in that causes development of generational attitudes and hence cultures. We have left the millennials in an overpopulated world, and they are reacting to cope with that. The philosophy is within our control, and that can comes after survival. We will learn to deal with that which we were equipped to deal with within our culture. Philosophy is the delta of calculus, the new change that each generation must deal with.