I am a big fan of Elon Musk and I generally think he has very good analysis, but I'd like to have seen his analysis for this because this seems poorly reasoned.
I'd disagree with every case. Elon Musk could not possible have research this very thoroughly. Especially claiming WWI seems nuts. Back in those days France, Germany and other neighboring countries had had many wars, but it was seldom about complete dominion. They stole some land from each other. Germany only planned to take some chunks from France and take over Belgium. Secondly Germany was hardly some crazy fascist dictatorship. Thirdly if you read discussion of this Americans don't seem to have had that much direct effect on the battlefield. Its seems like the allies would have won eventually, just slower without American participation. They controlled the sea and was ramping up war production way beyond Germany. And finally none of the above might have matter at all since the real end was the German revolution which produced the Weimar republic. The new democratic leadership was not interested in any war of conquest.
The US had more influence on WWII, but 80% of German forces got destroyed on the east front. The Soviet Union was a formidable opponent and it seems unlikely that they could have ever held it even if they had had more success without US support of the USSR. Germany was poorly prepared for occupying such a large country. Without the US the war would likely have dragged on longer but I think Germany would have had to give in eventually. The alternative outcome would likely have been an undemocratic Germany, however Stalin would likely not have had the strength to occupy eastern Europe, and we might actually have ended up with more democracies. This is what I hate about the rose tinted description of WWII outcomes. WWII started because Britain had pledged to keep Poland free. At the end of the war Poland was a communist dictatorship. So was all the other east block countries. So WWII didn't result in a lot of democracy.
The US surely stopped Japan, but Japan wasn't spreading dictatorship in a free world. They were frequently replacing one colonial power for another. Who knows China controller by capitalist dictatorship in Japan might have been preferable over a communist dictatorship led by Mao.
Finally the last assertion is on even shakier ground. Quite the contrary I'd claim the US mostly did things worse in the cold war. The Vietnam war was a big waste of resources. Vietnam turned capitalist in the end just like China. US meddling in Afghanistan during the cold war screwed up the country more and laid the seeds for modern day jihad. In some cases like Cambodia, US meddling more likely caused communism to happen than prevented it. Communism got rotten from the inside. They started stagnating in the 70s and economic problems got worse through the 80s while those living behind the iron curtain increasingly became aware that they were falling far behind the western democracies. Groups like solidarity sprung up in Poland. Communism got destroyed from the inside. The US was hard on the communist rhetoric but ultimately I don't think that was what mattered.
We can't prove it would end one way or the other for sure. But I think it is dangerous to end up in this kind of hero worship of the US. I think a lot of failed American policies has happened precisely because of the idea of American exceptionalism. If America had less inflated ego, it might have accomplished more IMHO.