Why did germany attack the soviet union

For Power and Territory -  Hitler regarded communism as Jewish Bolshevism. Hitler believed as part of his racial fantasies that communism had been invented by the Jews as part of a plan to take over the world. Consequently it was inevitable that he would invade Russia.

The reason that Hitler invade Russia was primarily based on his ideology. He believed that the Slavs were weak and would crumble under the German was machine making it easy to get oil and troops from Russia but instead Germany failed. Any other country who has attacked Russia especially in the winter months has failed miserably but Hitler's ego was so high he thought he could do it. Already fighting Britain and the US on one front Germany attacked Russia and lost poorly.