The DNC pushed for Clinton over Sanders, and they specifically helped Trump win the republican candidacy because they saw him as a pied piper candidate that couldn't possibly win any swing states.
Very important to analyse why Trump got the absurd amount of support he did. A lot of disgruntled non college educated white males in rust belt states swung to Trump for fear of their jobs and their way of life to foreigners, Trump got Wisconsin, Ohio, Michigan and Pennsylvania for this reason, nobody thought he could do that, the RNC couldn't believe he even bothered going to Wisconsin, these are blue collar democrat bread and butter. College educated males under 30 swung to republican in record numbers, why?? Alt-right movement and anti-feminist movement? Young men graduating college in America have 2-1 disadvantage at getting a job as equally qualified females as companies look to rectify gender disparities, That's driving a big anti-feminism push from young males.
Why any women, hispanics and blacks voted Trump I have no idea, but it's very interesting to note the massive discrepancy between exit polls and actual votes from females. The female exit polls were massively towards Clinton yet the actual votes didn't follow. So a lot of women weren't comfortable telling exit pollers that they voted for Trump - very interesting and very telling
Democrats lost the unloseable. Hopefully it will be the wake up call the party needs.