So who is responsible for that? But of course the citizens. For example, you live in Greece in 2017. Your wages have fallen, your children are unemployed, you have great difficulties. And you vote that the people responsible for solving your problems for the next 4 years are the Nazis? Are you serious? Ok, I can imagine that you are not Nazi. You are angry. But you put those people in the parliament to represent you? And help you how?
Should fascist and communist parties be legal in the Democracy?

To go further in this question, there is a very interesting book:

Götz Aly, Hitler’s Beneficiaries: How the Nazis Bought the German People, 2007.

In 1945, the Nazi power benefited from popular support because of the material advantages that the Germans derived from the policies of predation. This thesis must be nuanced, but it has the quality of integrating economic and social dimensions alongside ideology into questions of support for the system (social benefits, housing and employment policies). The political stability of authoritarianism and totalitarianism also stems from the negotiation between power and its populations.