After WW1, the nation of Germany was put under a huge amount of financial stress. I agreement with the allied forces, the Germans had promised to reduce their army down to 100,000 men, weren't allowed to have an air force and had to pay a debt of $800b, witch the country didn't have.
Due to this, the government was put under a lot of political pressure. Then in 1938 the wall street crash happened and Germany WENT BROKE. There was a famine and food became scares and the German population became sick of it.
So when a short man with a silly mu-stash came along and said that he could fix everything the German people loved it.