Credit goes to Professor Schweikart.
I have always thought we would have been better off not choosing sides between Hitler and Stalin but that we should have popped a LOT of popcorn, settled into comfy chairs and witnessed the result of "Let's let Hitler and Stalin fight." After their respective forces had annihilated one another and only one was left barely standing, send in Patton and finish off the surviving forces. No more Nazi Germany. No more Soviet Union. No Warsaw Pact. No European Axis. No Cold War (after WE have won). Spring training for our military would have been finishing off Imperial Japan while waiting for the preliminary result in Europe to determine whom we would be annihilating there.
There's an idea. I haven't looked at it that way. But might Hilter have kicked their butt without having to deal with us on the Western Front and then been in a stronger position? Imagine if he had stay allied with Soviets in the first place, ouch. (This is more interesting than the awful election.)
In other words, it was just as likely that we would have faced a vastly stronger Nazified Europe, with ALL the troops swung our way, armed with rockets, jets, and nukes. And STILL at war with Japan. Not a good scenario. No, you don't play "maybe" when your survival is at stake. You ally with the lesser of evils and worry about that one later.
Hitler was not terribly rational, He made grave errors in his war against the soviets. At first, when he sent only the Sturm Abteilung (young blonde, blue-eyed Aryans) into Russia's Western precincts, they were welcomed by the long-suffering soviet citizenry. Within weeks, he sent in the SchutzStaffel to round up the Jews. Backfired BIG TIME. Stalin had been forced to allow his people to march behind ikons of the Blessed Virgin and invoking not the Comintern but "Mother Russia." OTOH, neither the nazi ideologues nor the soviet ideologues were likely to yield to one another once blood had been shed. It would have been an epic battle with monstrous casualties, and then we would have been in an excellent position to, ummm, pragmatically capitalize on the situation.