When you come from a place of privilege, it's really easy to only care about things that affect you. And I'm not including just young people. It's true for everyone, it's just that young people on the Internet are the most vocal demographic ever. So when all the white so-called Sanders supporters in Arizona had to wait in line for hours to vote or were turned away because they registered as Democrats passed the deadline, all of a sudden they care about voter suppression, the same type of suppression that has plagued minority communities for years in red states. They were pretty silent when it happened I'm states Clinton won.
And in case you didn't catch my sarcasm, no, I don't think Millenials in general care about drone strikes in the Middle East and northern Africa.