The #1 reason that Hitler gained power was because of propaganda. Without propaganda, the unemployed would not have known about the Nazis in the first place, which would give their party power. A lot of propaganda was used.
The #2 reason that Hitler gained power was the unemployment rate during the Depression. The Nazis talked about radical changes that appealed to the unemployed, and got their votes.
The election was the #3 reason Hitler gained power. With the help of the unemployed the Nazi party gained an immense amount of power from the people.
And because everyone was drunk the end.