Following World War 1, many countries felt that their punishment for participating in the war was unjust. The Soviets did not support the king's war effort and decided to do opposite of him, the Italians were unhappy that the Allies didn't give them what was promised. The Germans felt that their punishment was harsh and degrading, while Spain had a civil war in which the Fascists beat the Communists.
I'll say the need of people to want their country to be powerful again played a big factor in people like Stalin, Mussolini, Hitler, and Franco were put into power.
