Sitting around whining and bitching from the outside of the political process gets you no where and people just get tired of listening to you whine and bitch.
As the Tea Party figured out, the game is not played as Democrats versus Republicans during the general election. The game is played as liberal Democrats versus Republicans-lites during the primary election. Then once the die is cast after the primary, you're doing nothing but surrendering the field of battle to the out-right aristocratic imperialist Republican Party if you don't work to get the Democrat elected regardless of the Democrat's stripes. In situations where there's a really bad Democrat, they are inevitably facing off against a horrendous Republican.
Getting the liberal Democrat elected in the primary and then following through with a win in the general moves the ball down the field. If the Republican-lite wins in the primary, getting that Republican-lite to win against a horrendous Republican is playing defense. It is trying to hold the line and stop the ball from moving (or at least minimize how much) in the wrong direction until the next election.
I'm a Bernie supporter with some concerns about his electability in the general election, but I'm still a Bernie supporter. If Hillary wins the primary, I'm going to work to get Hillary elected just as much as I'd work to get Bernie elected. If nothing else, I feel reasonably satisfied Hillary will make the right SCOTUS nominations.
Bill Clinton's SCOTUS nominees voted against the expansion of political corruption and bribery while all the Republican nominees voted in favor of expanding political corruption and bribery. While certainly Bernie will appoint nominees who'll vote against the expansion of political corruption and bribery, I have every confidence Hillary will as well.