Over a number of decades, I have taught undergraduates, coached up-and-coming executives, listened to the groans and complaints of people starting their career, and started a consulting firm with a group of New York hipsters, so I have had a unique opportunity of having mentored several generations.
None have intrigued me as much as the Millennials, but I don't subscribe to the idea that they are that radically different. Being hip, cool, and fast have been around for a long time. Working in real time rather than methodically planning has always been part of the game. Ambition is not the exclusive realm of the young generation. Nor are quick fixes and pithy language.
That said, much of it has gone a bit to the extreme. What Millennials need is not a change in behavior, but to nuance their behavior. This is not to say to Millennials to put your ambition back in the closet or suppress your bravado. Don't stop working in real time. Certainly, don't stop having a sense of entitlement. My advice is just to nuance your behavior.