The biggest damage Hitler and the Nazis did was stop a genuine Communist revolution within Germany. Had Germany genuinely gone Socialist, it’s very likely other highly developed Capitalist countries would have had revolutions as well, and not just the underdeveloped countries like Cuba, China, Russia, Korea, Vietnam, Laos, etc. Had Western Europe gone largely Communist, only the US would really stand as a bulwark of Capitalism, separated by the Ocean, at which point it would have been only a matter of time.

That’s not even to mention that the Holocaust would have been stopped before it happened, and the USSR wouldn’t have had half of its dwellings destroyed by the Nazi invasion. The Soviets would not have had to focus so much on rebuilding, and likely would not have had to spend so much of their overall GDP on Millitary R&D to keep the United States at bay during the Cold War, crippling their economic growth and eventually leading to dissolution.

Israel as a genocidal project would likely not exist either. Palestine would be free.

I can’t understate how different history would look today had the Communists succeded in Germany.