In the early 1930s many people in Germany and throughout the world were simply incredulous at the idea that Hitler would come to power. Mussolini had already come to power and more or less constructed a police state. But Mussolini was a bit of a buffoon and Italy, in its own right didn't really constitute a major military threat. Hitler, on the other hand, was no buffoon, and even though Germany had been badly damaged by the First World War, people in France, England, Russia, and the US, knew that Germany was a significant industrial power and could pose a significant and existential threat to many nations.
But Hitler's rise to power might be seen, in some senses, as inevitable. Many Germans felt deeply betrayed by their leaders and the Entente Alliance at the end of the First World War. Conservative Germans felt as though they were losing the Germany they knew; they felt that they were far too indebted to the Alliance, that they were being played, and that the Weimar Republic was degenerate and perverse. For conservative Germans, Hitler represented the old Germany, the good Germany of "law and order," of proper German culture and religion, as well as a resurgence of German industrial and economic power. In order to get power, Hitler traded on these nationalist feelings, he whipped up racism knowing that the Germans who felt that they had been hard done by a the end of the Great War would lap it up. Hitler promised to make Germany Great Again, and he used nationalist and racist rhetoric to sell that promise.
The sane people in Germany and elsewhere understood by instinct what Hitler represented. While the Western powers were far from perfect, particularly in the colonial efforts, Hitler represented a level of threat that arguably very different, and one that smart people knew was overwhelming.
I think that smart people understand what kind of threat a man like Trump represents. His rhetoric is shockingly similar to the fascist rhetoric of the 1930s. There is here, I believe, an existential threat to society, and it revealed by the rhetoric of racism, violence, misogyny. Like the fascists, Trump shifts the blame for social problems on outsiders and a supposed elite. He denigrates anyone who opposes him as a social enemy or a criminal. He talks of reinvigorating US industrialism and economic power but always against a backdrop of "foreigners" who "steal" American jobs and prosperity.
Trump is a profoundly dangerous man who may very well win the white house in 8 days. And just as people in the first two months of 1933 were incredulous and found it hard to believe that Hitler would really consolidate his power through the ballot box, many people at home and abroad today think that the words "President Trump" are just too hard to believe. But history is an ugly business.