In fact if the SS hadn't been such unbelievable monsters, it's liable that the USSR would've collapsed under everyone's loathing of Stalin in the first place. Hitler himself expected the country to fall apart under its own internal inconsistencies (and the devastating effects of Stalin's purges on Soviet military capability,) he just didn't grok that sending groups of murderous thugs around to murder as many babies and elderly as possible was a great way to unite the opposition.

Same story in Japan. If the Japanese had just been a bit less brutal and dickish in conquering China they could've easily gotten Chiang Kai-Shek on their side, he long regarded the Communists as a greater threat and basically had to be forced to form the unified front at gunpoint. There was a lot of potential for goodwill towards Japan as an Asian nation kicking out the colonizing powers from not only China but South-East Asia as well, but they squandered it pretty cheaply.

And then dragged the USA into the war. Same thing with the Nazis and Barbarossa. The Axis had the best militaries, the obvious joke about Italy aside, but they had a very poor understanding of psychological warfare as a versatile tool. They could terrorize a populace, but they couldn't figure out that sometimes you don't want an enemy population scared shitless, you just want them to shrug and resign themselves to a different group of assholes being in charge.