People went Trump because neither the Democrats nor the Republicans have done anything to help the White Working Class in the last 40 years.
They got enthusiastic behind (I) Bernie Sanders and (?) Donald Trump, both of whom ran insurgent campaigns from within the two major parties. But only Trump was bare-knuckle enough to break his establishment rivals (it helped that they were fractured between 15 candidates).
Had Bernie ran against Trump, we would have had a true Populism election.
All Trump had to do in the end was beat The Machine, and he had plenty of practice at that in the primary.
The Middle Class has lost faith in both parties.