I have a sense that personally, Sanders just isn't a nice guy; I don't know if that's just a gut thing or if there's something I've read but forgotten. Not in the trump way, but in the "That isn't a priority with me" sort of way.
I'm running to catch up with this thread, but even though I haven't finished reading all the posts, I'm jumping in here because it's such good intro to my views on Bernie.
First off, I suspect he's not quite neuro-typical. So it's not so much that he's not a nice guy as he's just not that interested in (or possibly even capable of) conventional social interactions. He has a life-long passionate and narrow focus on income inequality (also a tell for someone on the Aspie continuum), and that was his motivation for running. He's not motivated by greed or desire for power, he's got his eye on the prize of righting a wrong.
That focus is exactly why I'm glad he ran in 2016 -- he brought my top priority issue to the fore, and I think his influence was invaluable. In my view he strengthened HRC more than he undermined her. The Bernie Bros who didn't vote for her would NEVER have voted for her.
So to my mind it's unwarranted to blame Bernie for Clinton's loss. HRC made some poor judgment calls, which in the context of a fair election might never have cost her the presidency. But in a year rife with voter suppression and Russian influence, her misstep in key states -- taking her support there for granted -- was just one papercut too many. The GOP's corruption had FAR more effect on the outcome of the election than bitter Sanders supporters.
All that being said, Sanders would probably not have been a stellar president. Not as bad as Trump, but that's hardly a measuring stick. Presidents have to have a wide focus and just don't think Sanders could have made that transition away from his primary concerns. Fast-forward four years and he's just too damn old. We have much better choices this time around, with more candidates focused on income-inequality issues. I wish he wasn't running again because I think he will dilute his own cause.
On the other hand, this is what primaries are for -- to throw all the options out there and see what sticks. I applaud a wide field. The more the merrier. I don't buy the argument that the wounds inflicted in the primaries are fatal for the general election.