They’re good at throwing their population into the meat grinder, sure.

They really did the bulk of Wehrmacht killing on European mainland. But they didn't collapse only due to massive US support, be it in armament, equipment, medicine etc. Absolutely massive. Also it was basically due to bad German planning and preparation for winter, not some soviet strategic brilliance, which was very hard to be found on eastern front, just meatwave after meatwave till german machine gun barrels literally melted.

You could see tons of US equipment during WWII reels on eastern front including heavy machinery, soviets tried desperately to remove such footage (just like photos of soviet soldiers wearing 3+ watches on each hand... err borrowed from friendly locals) but truth has this behavior of seeping back to light.

Capitalism works pretty well in any moral society actually, much better than any other system thats for sure.

If you look how capitalism is actually implemented, it always has bigger or smaller kleptocratic component.