Because if people in the middle can be so damn gullible to vote for a criminal who said:
"I don't care about you, I only want your votes",
like Trump because he promised good economy I don't know how anyone can conclude that the issue here is with democrats and not the people's lack of critical thinking.
It's a bit late to correctly point out that focusing on demographics as you voter base is stupid and that it's interest groups you should focus on (as this should've been done in 2008 after Obama's victory), because this isn't a race between two sane candidates.