Obviously in hindsight it was a bad idea to invade Russia and make them an enemy. From my understanding, Russia was supplying them raw material to fuel Germany's war machine. But Germany wanted those resources for themselves and invaded Russia. I wonder til this day if Germany had not turned on Russia, where would they be right now. Russia was the reason why Germany lost footing and turned back to Germany as the lost the battle of Stalingrad. Could they have continued to buy resources from Russia or found other means to resupply themselves?
With respect to the war in Europe, that is likely the biggest question of them all. Many historians have bandied about different scenarios of a delayed, or even cancelled, Operation Barbarossa. Some hypothesize that it would have dramatically changed the course of the war to the point of an Axis victory, while others believe it would only have given Stalin time to amass his forces for his own crushing invasion of Europe. Some books that I can recommend that touch upon this topic are: Germany and the Axis Powers: From Coalition to Collapse, by Richard L. DiNardo Why the Allies Won, by Richard Overy Axis Power: Could Nazi Germany and Imperial Japan have won World War II?, by. Dr. William Roger Townshend, Ph.D Interesting topic and I believe one that could yield some interesting discussion.
Advancing on Russia was expensive. I'm assuming as they took over land they controlled and used whatever Russian resources they came upon. Beside Russia, who else was selling or trading resources to them?
Access of raw materials to Germany is a complicated and important factor in the war. On paper, they controlled huge amounts of resources in occupied and Axis-aligned Europe. In reality, the extraction of said was hampered by the grim realities of the war. However, to the question, there were a number of sources. Romania, an Axis member, for example, supplied a great deal of petroleum, oil, and lubrication. Sweden, a neutral nation, sold badly needed iron ore to Germany. And there are other examples.
It was only a speculation or perhaps propaganda that Stalin's goal was to conquer Europe. Russia might be "expansive" in the near past, but there was no indication that Stalin wanted world domination at that point in time. If Nazi Germany did not invade Russia, it would certain give Stalin time to build up his forces. The Russians were in the middle of a major military modernization program by the time the Germans invaded. So if the Russians had a few more years, it would make them a more formidable opponent if the relationship had gone south between the two sides. In my opinion, the Euro-Asia (as well as Africa) would be dominated by Germany-Russia-Japan if that was the case (German stayed friendly with Soviets). I am not saying they won't ever fight each other after they completely secured the three continents. But by the time the have dominated the huge land mass, not even the US with the backing of entire Americas could do much about it.
