Why did the Germans betray the Russians?

This was because Hitler was getting so confident in his war since Germany had been having non-stop victories that he ordered 4 million of his men to invade the USSR. They wanted all that big land and oil that Russia has and thought they could beat the Russians, just like they beat everyone else. But this plan failed and the invasion went on into the deadly Russian winter, where many of the Germans died. Eventually, the Soviets pushed the Germans back into Berlin(1945) where they defeated the Nazis. Without the Soviets, a lot more good men would have been lost to the Nazis' idiot war.