The answer is simple. Voters just plain don't trust Hillary which is very much a part of the Establishment they also dislike.
This is evident by the way the Democratic Establishment has been running this campaign; diligently working to rig it against Bernie Sanders who is overall not only the most favored candidate, but is genuinely trustworthy and honest. Someone that neither side of the political Establishment want's in politics or the Oval office.
Political analysts have underestimated Trump from the jump because they’ve been looking through the rear-view mirror of politics as it used to be.
Trump’s rise suggests a new kind of politics. You might call it anti-politics.
The old politics pitted right against left, with presidential aspirants moving toward the center once they cinched the nomination.
Anti-politics pits Washington insiders, corporate executives, bankers, and media moguls against a growing number of people who think the game is rigged against them. There’s no center, only hostility and suspicion.
Americans who feel like they’re being screwed are attracted to an authoritarian bully – a strongman who will kick ass. The former reality TV star who repeatedly told contestants they were “fired!” appears tough and confrontational enough to take on powerful vested interests.
In this era of anti-politics, any candidate who appears to be the political establishment is at a strong disadvantage. This may be Hillary Clinton’s biggest handicap.
The old politics featured carefully crafted speeches and policy proposals calculated to appeal to particular constituencies, such as female boomer college graduates or Latinas under 40. In this sense, Mrs. Clinton’s proposals and speeches are almost flawless.
But in the new era of anti-politics Americans are skeptical of well-crafted speeches and detailed policy proposals. They prefer authenticity. They want their candidates unscripted and unfiltered.