I'm talking about the millenial movement. Bernie's sentiments align with a majority of the U.S.'s young people. Hell, they even align with young people from other countries; I have two cousins in Germany with dual citizenship who are 19 and 22 and support Bernie.
Entire books are being written about marketing to youth culture (i.e. YouthNation). The world is becoming more and more youth-driven, and Bernie understands that. He is, like I said, seizing the moment flawlessly by getting his ideas out to the right people at the right time. This subreddit in itself is a perfect example.
Edit: After a shower and some thought, I do have to admit that my original statement was quite the hyperbole. FDR is a great counterpoint to what I said. Nevertheless, I do think Bernie is running a groundbreaking campaign.