Hitler's most idiotic move
I'm impressed by many of the intelligent replies in the threads here. People who are familiar with history already know this: his downfall began with his idiotic decision to invade the Soviet Union. Like Napoleon, hubris caused him to think that his armies could survive the "war of attrition." Granted, the nazis were initially decimating the Soviets, but as they are known to do, the Russians just withdrew deeper into the country and let the winter kill the invading forces.
I literally shudder when I consider what would have probably happened to England if he wasn't stupid enough to wage two wars against those two powers at once. It also began Stalin's literal obsession with killing him. It was just stupid all around. The Soviets had no intention of interfering with him prior to the invasion.
Also, in the movie he says, "the east will eventually triumph over the decadent democracies of the west" -- wrong again, dumb--s.