How progressive is someone really, when they're against everyone who isn't like themselves? Food for thought.
Meanwhile, the Democrats are a 'big tent' party that values inclusiveness and working together. Bernie supporters don't share those values because of their ideological purity requirements, and so the Democratic primary voters chose another candidate. Particularly women and minority primary voters, who Bernie didn't reach out to because his support base are mostly white males who don't care if Trump gets another 4 years because it's not their civil rights getting bent over.