As I’m an Austrian that of course is a very difficult question. It is often asked in our history education-lessons, because teenagers today can’t really understand why their great-grandfathers were able to do such horrible things or why they at least fought against it. I will try to give you a short summary of the answer to your question:

But first you have to look at this issue with another mind-set. These people didn’t have a good life. As the loser of WWI the economy was badly damaged and the people had nothing. Also the democratic system of Germany and Austria at that time didn’t work properly and the people were disappointed. Then there was the problem of being “leaderless” without the “Kaiser”. If a state is forced into democracy through other countries and is robbed of the system that worked for most of the people, but being left at the same time with nothing but debts (reparations payments were quite high) and a ruined economy after being the biggest industrial power of the world (referring to the German Empire), it is comprehensible that the citizens of the Weimar Republic weren’t fond of their situation.

And then there were people that promised a better life and jobs if you vote for them (at the start the NSDAP was just a political party like every other at that time).

At first it even worked. The country had an economic boom and the rate of unemployment declined. Of course not everyone was happy and there were groups that fought against the growth of National Socialism, but they weren’t big enough and the NSDAP gained more and more power. When the Weimar Republic turned into a dictatorship it was way too late to vote against it, because other parties were forbidden and Hitler and the Nazis were already reigning the country.

Still, it is easy to say today, that these people should have known the consequences and that more people should have done something to prevent it, but that is our mind-set. We didn’t live back then and when it was obvious what the Nazis were doing, you would risk your life and that of your family if you said something against them.

The same goes for Austria. Before the “Anschluss” (German for “to fuse with something” or “to join someone”) happened and German troops marched into Austria there was a “vote” if the citizens want that and nearly no-one dared to say no, or they just didn’t realize the consequences.

So to answer your question: the people didn’t vote for a dictatorship, because when it was plain to see where the train was going, it was already too late.