2) He is one of very few people in the political world who can make Hillary’s politics seem more moderate
More importantly, though, Sanders helps Hillary Clinton seem more moderate. Yes, she’s one of the wealthiest women in the world and she’s trying to raise $2.5 billion (with a b) to vanquish GOP opponents. Yes, that money is being raised from corporatists and cronies on Wall Street. The party’s nomination she seeks, however, is in a moment of not liking all this cronyism.

Hillary’s been worried about holding off Sen. Elizabeth Warren (D-MA), a more populist progressive. So she’s been saying stuff about “toppling” the wealthiest one percent.

By being so extreme — insofar as being a democratic socialist is extreme — he makes Hillary’s close ties to Wall Street seem a safer bet. And she can continue the class war rhetoric and point out that she has a legit U.S. Senator who is far too her left, letting her attempt the old Clinton triangulation.