I'll just admit that I have misread (or missed) just how much the establishment left hates Sanders. Far left MSNBC is going nuclear on him. It's kinda entertaining to watch.
They don't hate him, per se.
They hate that he's saying what they really want to do. For 40+ years their modus operandi has been to lie lie lie and move everything towards total control.
He's giving away the game too soon. (Hopefully, but probably just barely too soon.)