I am not sure if this question has been answered

[Garrett78]

13. I think that's a big part of it.

Similar candidates have run before but not had as much success (Kucinich, for instance, has more or less the same views as Sanders). I think Sanders saw an opportunity to take advantage of a chaotic political climate, to take advantage of a collective frustration with neoliberalism (even if some don't use that term), and figured he might be able to force Clinton to be held accountable once she's nominated and then elected (being the heavy favorite that she was when the campaigns got started). Rhetoric and policy are 2 different things, and even Sanders would end up compromising some of his stances were he to get elected POTUS, but by running a fairly successful campaign, greater pressure will be placed on a Clinton Administration to operate in a more progressive fashion than it might otherwise. But it's not really about the individual so much as the system. The likes of Clinton, Obama, Kerry and Gore are symptoms and not causes.