Frances Coppolla has a compelling article on this very topic.
It looks at a new paper on the topic. Like Frances I always thought that the terribly high unemployment rate was the main reason for this.
Nope. It was the middle and upper classes that voted for the Nazi party.
I might note two separate things.
First even Hayek recanted on his support to Bruning's fiscal policies. He even supported some increase in public works expenditure.
Second austerity done at the correct time is good for the economy. Keynes told us back in 1936 when to do this. It is when the economy is doing well. Keating did this in 1987, Costello did this in 1996 here and Clinton did this in the mid 1990's in the USA.