The allies were formed by none other than Russia (almost inexhaustible source of human meat to be thrown in the slaughterhouse) and the United States (country with the largest economy and largest industry in the world). As the word goes, Hitler let the British evacuate their men from Dunkirk, as a result these same men land in Normandy to the despair of Hitler and joy of the French.
Hitler became obsessed with conquering Russia and mainly Stalingrad, refused all requests from his generals requesting permission to retreat, as a result millions of valuable and experienced soldiers would be killed or captured on the eastern front.
Hitler became obsessed with bombing civilian targets in England instead of strategic targets like air bases, ports, factories and so on. As a result, the air force would lose some 1,500 valuable aircraft and experienced pilots who could have made more of a difference on the Eastern front.
The weight of Hitler's misguided decisions was such that he would have to fire one of his best strategists, Franz Halder, because he fiercely opposed Hitler's interference with the original plans of Operation Barbarossa. The same Franz Halder wrote something about this in "The Halder Diaries" if I remember correctly.
This story comes down to a corporal called Hitler vs. Experienced Tactical Academic Experts of the German Armed Forces. Years of study and research were nothing in the face of Hitler's egomania, a mediocre corporal who became the leader of the German nation.
For Sun Tsu, Hitler would be the perfect opponent, unstable, predictable and egocentric.
Yeah, just no. You are basically taking all the excuses some German generals came up with after the war to shift the blame from their own failures onto Hitler, regardless of whether those claims make any sense or not.
Stalingrad didn't lead to "millions of soldiers getting killed or captured". The number wasn't anywhere near that high. The decision not to retreat didn't come out of nowhere either, nor was it just a mad decision. It was based on the experiences during the winter of 1941, where the order to stand fast and work with strongpoints that the enemy might be able to bypass but not get any supplies past ended up working out. It might actually have saved the front from collapsing. Granted, it wouldn't have come to that situation if they had stopped the advance earlier, but it is still a mixed bag of decisions. Being able to halt the Soviet winter offensive, cutting off Soviet troops that got past the strongpoints, and supplying and keeping the Demjansk pocket alive where seen as proof that this could work in future situations as well. Which ignored that the losses, especially in terms of transports, weren't really sustainable, but still, there were arguments for that strategy to work. An additional problem in Stalingrad was that most ofthe horses had been pulled back to improve the supply situation. There wasn't really a need to keep all the horses around for what was mostly static street-fighting. That meant that when a breakout was necessary, the necessary mobility just wasn't there. Now this is obviously a flaw, but then again, keeping the horses at the front would have meant far less supplies at the front, which in turn wouldn't have been any better either.
The real problem came from 4th Panzer Army being pulled from the approach to Stalingrad to support the breakthrough at Rostov, only to be order back a short while later. This back and forth kept the army from doing anything useful for two weeks, which in turn caused the planned encirclement and destruction of all Soviet armies in the Don area to fail. That was actually the main goal of the push towards Stalingrad, to destroy the armies. If that had succeeded, the whole operation towards Stalingrad might actually have taken the city without prolonged fighting.
Halder was hardly a great strategist, and he most definately was one of the most guilty ones in terms of whitewashing his own failures. To act as if the military was one coherent force that all agreed on what would be best, while Hitler just ignored that, is simply not true either. There were vastly different approaches among the military leaders. Some thought taking Moscow should have been the main goal, some though Moscow was entirely irrelevant, destroying the army was that mattered. Some thought attacking in the first place would be a mistake. Not once was there a time when everyone agreed on what would be the best plan. Needless to say, without Hitler you also don't have the Sichelschnittplan that leads to the collapse of the western allies. At that point, he was the one who opted for such an approach, even when some military leaders tried to push that idea aside. It was also von Rundstedt who stopped the advance towards Dunkirk. Hitler just ended up backing that order after being angry about not being informed about the decision made by OKH. This was mostly a case of OKH not being able to inform him as he was travelling, and von Rundstedt getting to him first.
There were countless decisions by Hitler that that were highly questionable to downright bad for the German army, but also plenty of times where he was right and generals who argued against him weren't. Just like some generals didn't think at all about what it actually takes to fight a war on an industrial basis. Hitler did end up taking more and more control in the later stags of the war, which ended up sabotaging the capabilities of his armies due to removing the decison-making from those right at the front, which had been a strength of the army, but to act as if he was some bumbling fool who kept his brilliant generals from being successful just doesn't line up with actual history.
There also was absolutely nothing predictable about Hitler. If anything, he was the exact opposite.