[faeriechangling]

>How did “not my war” turn out in the 1930s?

For the Americans? I'd say their policy of being a "neutral" arms dealer mostly made the Americans a ton of money and rocketed them to global superpower status. Now Japan did attack them in a hostile action but America kind of pounded them after so I'm still not sure "neutrality" worked out so badly for them. If anything the Americans started doing worse and worse the more and more they got involved in wars halfway across the world.

For the Brits? Yeah appeasement was kind of a policy failure, Hitler turned out to not be the most trustworthy chap. I dare say Hitler was an unscrupulous chap.