Remember, Hitler and the National Socialist's were voted into party thru democratic means, although to be sure, democracy was never really a part of the German zeitgeist back then.
All the major players knew the ToV was going to lead to another war, and it sowed the seed for the rise of some sort of militaristic, Fascist government.
More generally, if I vote today for X and tomorrow X turns out to be a murderer, will you hold it against me because I can only vote every 5 years?
Anyway, any equivalence between what is going on now the ME and what Hitler and the Nazis were doing back then is totally false.
So in that case, it seems voters knew exactly what they were getting (and eventually got) with Hitler.
Obama, not so much...obviously.
The fact that there is such a disconnect between the actions of government and the will of the population shows how flawed "democracy" is.
As compared to what?