I won't say Bernie supporters weren't a factor, but the prospect of "buttery males" was an easily measurable factor. Trump was having a really rough few weeks running up to the election. He had a piss poor debate showing, the Access Hollywood tape, and sexual assault allegations all coming together against him. Even with Russia laundering their hack of John Podesta's emails through Wikileaks and Wikileaks working working with the Trump campaign to drip out the hacks, Trump was well behind. It was hard to see anything with Bernie supporters because that played out over the entire campaign. Meanwhile, the Comey letter had an immediate effect over mere days.
Clinton was giving paid speeches to wall street
Note that Clinton's speeches were from well before the campaign. When I looked at the transcripts when they got released as part of the Russian hacking, I could see why she didn't want them released. There were parts where she was being more frank about certain subjects than politicians usually are. It was easy cherry pickings from there. And as much as the paid speech circuit has its detractors, I'd rather see former or dormant politicians giving empty platitudes to rooms full of bankers than lobbying their former colleagues.
she was saying keep things the way they were
At the very beginning of Hillary Clinton's campaign, she did a tour of the nation and just listened to people's problems and concerns. From there, she drew up a platform. She has a history of doing this sort of thing like when she was a senator in New York, where she tackled loss of jobs in upstate New York in areas that had been ignored.
She also was pretty blunt with certain areas, like talking in West Virginia about needing to plan for a future after coal. To his credit Bernie didn't jump in there to attack her, but he also didn't exactly jump to cover the subject. Trump of course did, lied to the workers, got their votes, and they're still losing jobs anyway.
And it all came to a waterfall moment when Sarah Silverman was on stage. And people were chanting Bernie and she lost it and told everybody to shut up and said the Bernie supporters were stupid.
She shouldn't have lost it, but I can see why. I remember Bernie supporters in general getting extremely annoying around that time. It's the same attitude that we saw out of Trump supporters: everyone I know loudly supports Bernie/Trump, no one I know supports Clinton/Biden, therefore I was cheated. I couldn't poke my nose up on /r/politics in support of Clinton without getting my face gnawed off.
And that was it. The only thing that came out of it was somebody got fired, but there was no regard or representation for us in the Democratic Party anymore.
There was supposedly a takeover of the DNC by the Clinton campaign. This is a questionable interpretation. tl;dr: A heavily indebted DNC traded fundraising by the Clinton campaign for some control. Nothing stopped Bernie from a similar deal. Also Donna Brazile told the Clinton campaign that there would be two questions: one on capital punishment and the second on lead in drink water. I'm sure she had a stock answer for capital punishment. For the second, the town hall was in Flint, Michigan. Yeah, of course they're going to ask about lead.
For me it was a massive dissolutionment, and drove me to Trump. Since he was saying we need to take our economy back from the 1%.
Did Trump ever actually say that? I ask the question because Trump does this thing where he leaves himself as a blank canvas. Two supporters with different values can believe contradictory things about Trump without there actually being evidence of a contradiction because he either never said anything or because he just says things without meaning them.