Looking all the way downstream, to the end result (voting numbers) is much less valuable vein to mine for insight than how he was portrayed in media, online and in legacy media, before votes were cast. That provides much more insight in to how his campaign failed, in my eyes at least.

I don't have all the historical polling data to say this with certainty, but his policies were pretty much always supported by a majority of the american public from a cursory perplexity search (grain of salt and all that, but seriously, can you think of one policy of his that wasn't popular?)

The more important question, to me at least, than "in 2016 did america think bernie was a crazy leftist?" is, "why, when his policies all had majority voter support, did the candidate himself carry the McCarthy era veil of 'crazy leftist' and 'communist'"?

And I think the answer is the same as in my original comment, a concerted effort from the billionaire class (who own all our media) to do anything BUT accurately portray the guy who vocally wanted to cost them money in favor of those who wanted to enrich them. I think the billionaire class almost always plays a bigger role than we think, but that might just be all the books I read about the machinations of the rich and powerful to manufacture consent. I'm no expert.