a campaign can't win if its ideas are both polarizing and espoused by less than 30% of the target population. if someone fundamentally opposes the concept of universal healthcare, all the marketing in the world isn't going to change that.
See, I would argue you’ve thrown out there the perfect example of why Bernies campaign was bad. “Medicare for All” is wildly popular even among a stunning group of GOPers. A public option, even moreso. Want to know what is supported by less than 30% of the population? Banning personal health insurance. And that’s what Bernie chose to demand - and would make no compromise on with regard to his platform.
A lot of the general principles of Bernie’s ideas have wide support, but he also demanded the most idealistic, narrow specific version of them. He had four years to build a coalition around 90% of his platform and he would tolerate no compromise, no middle-ground. He was only open to people joining his coalition if they unquestioningly decided he was right on everything and passed a purity test. He attacked his closest ideological comrades.
And that is why Bernie supporters continue to say he was cheated and it was rigged — because to be a Bernie supporter in 2020 means being a person who believes Bernie is always right and anyone standing in his way must be 100% wrong. Same as Trump supporters. Same as David Koresh’s supporters. The cognitive dissonance is so thick you can cut it with a knife.