Two main reasons I don’t care about Sanders:

1. He’s not going to win the election. He’s not even going to win the primary. And he’s not doing a great job, from what I can see, of forcing the candidates who might win the primary into taking his issues more seriously.
2. I have long been cynical about politics. I understand why politicians lie, why political progress is slow, why extremism or idealism in a leader won’t get us anywhere (and probably wouldn’t be a net positive anyway); it’s not a cynicism borne of thinking they should do better, it’s about knowing they can’t and not falling for it. I got duped, once: I bought into the whole Obama idea, the hope he was selling, etc. And he — of course, and inevitably — did not bring that to bear. Not that McCain would have been better: he probably would have been worse. But, I think that it’s intellectually dishonest to think both “all politicians are [perhaps necessarily] liars or double-talkers” and “Bernie Sanders has morals and ideals and would stick to them if elected president.”