The internet. "Millennials" are just much more aware of possibilities of life; both good and bad. The years of listening to a few group of elders and working hard to do exactly what your Dad did are over.
There's much more pride these days; whether it's justified or not. Working your ass off for a moderate income at a job that crushes your soul to provide for your family isn't a source of pride anymore.
My point? Millennials aren't any more lazy once they discover something worthwhile to pursue, it's just that they are more stubborn to declare something worthy of their full effort.