I'm going to speculate on the reasons for the demographic divisions between Hillary Clinton and Bernie Sanders supporters.
There's been a fair bit of bloviating going on recently about why young people (folks under 45) overwhelmingly prefer Bernie and geezers (or about to be geezers) like Hillary. Well, I'm a geezer but I, too, prefer Bernie. I have a hunch some of my reasons why would resonate with the younger demographic. In a nutshell, Bernie is giving us a pep talk about possibilities; Hillary is telling us to start being grown ups and settle for what we've got now. Every time she opens her mouth she sounds like someone's pessimistic grandmother reminding the kids that they'll get hurt if they try climbing trees, riding a bike, or doing anything else they've never done before. She nags, she gives you the old "We can't afford nice things" speech, and then wonders why 20-somethings are turned off. Geez, I'm turned off and I'm only a year younger than she is.
It's kind of odd, considering Hillary is actually the younger of the two, but she comes across as old and sour compared to Bernie. Bernie's not always a bundle of cheer either, but he definitely seems a lot more in touch with what younger people are hoping for. Bernie's telling us we can do anything if we just pull together and try; Hillary says dump the dreaming and accept the status quo. You know, pragmatism can be a good thing, but it should be the fallback position. No one should be told to settle for anything until at least a few attempts have been made at achieving something better. Hillary comes across as wanting to settle immediately, which might be a winning position when you're trying to shake campaign donations out of Citibank but it doesn't go over real big with millennials.