Just stop it. Some of you portray him as a racist, hatemongering, demagogue, whose only intent is to destroy America. There's already one candidate in this race like that right now, and if we are going to defeat him then we better unite.
Well I certainly don't support such over-the-top comments (like he's a racist/sexist/etc, i think he is a good man overall, tbh), but people are angry that he has stayed in the race long after his path to the nomination was effectively cut off, and he spent that time attacking Clinton (the actual presumptive nominee) despite the virtual impossibility of getting the nomination. So that has to be factored in here. He's the one continuing to keep the party split right now, and if he really does carry this to the convention, he'll leave only a few months for the party to get over this primary. That's very sh**tty of him because it'll all be for nothing.
I think Sanders had every right to stay until Hillary actually got the magic number (much like Huckabee did in 2008, despite his path to victory being dead already). Given that she essentially reached the threshold just before these primaries, I think he should definitively at least suspend his campaign tomorrow.
That being said, this behavior and behavior of his campaign, especially now, is quite foolish. They're only risking that all their efforts, all raised issues are going to be wasted. It wasn't supposed to go that way.