They concluded Trump was the answer because he happened to be running against the most unpopular candidate in history. It also helped that Clinton team ran a terrible campaign. Make no mistake, if Jim Webb had been the nominee, he would have cleaned Trump's clock. Yes 72 is right about how Trump connected with people. He spoke in a non-political vernacular which allowed him to communicate with voters in a very visceral way.
This and a few examples:
Many of the crossovers (from Obama to Trump) were tired of being ignored by the party. Both Obama and Clinton told them "your livelihoods are relics of the past; the government will help you instead". These are proud working people who were being told to in effect give up and move on under the "caring protection" of the government.
The Dem party increasingly became obsessed with fighting for "marginalized" communities rather than working middle class families. Policy emphasis was placed on illegal immigrants, refugees, transgendered, etc. Nothing wrong with supporting these groups but it became the primary focus of the party.
The final straw was the deplorables commentary. Hillary suggested if you didn't buy into D policy as outlined above you were an "irredeemable" person who was "deplorable".
Basically, the Dems drove a key part of their base away in an attempt to mollify and attract a coalition of marginalized communities.
Trump stepped in and said - I'm going to get your jobs back, I'm going to focus on the citizens of this country rather than prioritize the citizens of other countries and I'll help you recreate the American Dream that Dems are saying is gone for you and will be replaced by government programs.
It's just like Carville's "it's the economy stupid". Dems took a key part of their base for granted and ran an uninspiring candidate who had no message other than "it's my turn or it's a woman's turn".
The result is that a highly flawed guy like Trump won in the most unlikely election in recent history.
Or it could have been the Russians...