Questions on rise of Nazism in interwar years

One still very popular theory that purports to explain the rapid rise of Nazism in Germany in the interwar years is that there were a number of 'mentally deranged' and demagogic individuals who misled and also stirred up the population. But, why was the larger segment of people, including highly educated scientists, during the period so susceptible to the Nazi views on the past, present and also future of their 'race' ? Were there not some legitimate grievances, fear and anxiety among the Germans in the period ? Were Britain, France and other Western allies not too harsh in the treatment of Germany which was defeated militarily in the First World War ('1914-1918') ? What were the social impacts of the Great Depression in the 1930s on the German society and the new elites' political ties with their counterparts in the West ? Asking and answering these questions could help younger students of world history to be more balanced in the understanding of the theme, and able see more clearly the limit of some over'-simplified accounts.