This is basically American politics in a nutshell. I don't think any of us really understand it. I can't remember the last time we, collectively as a nation, thought "This candidate is really good, I hope they win. Oh but this one is really good too!" It's always a choice of which candidate offends your sensibilities slightly less than the other -- the whole "giant douche vs. turd sandwich" canard.
Hillary Clinton at least had the gimmick that she would be the first woman. One of the few things that made me almost stop supporting Bernie was when he endorsed Hillary. I lost a lot of respect for him, but I see his side too, Trump has been a disaster.
I dunno, having been around at the time, the hatred for Hillary was unlike anything I've ever seen. I would say that it even surpassed the hatred for Donald Trump, but that's not exactly true, as Hillary won the popular vote by over 3 million votes.
Bernie did the polite thing by endorsing Hillary. It's a testament to him being a stand-up guy, which is a good quality in a leader. Even if Hillary and her pack continue to trash Bernie, he's not stooping to her level.