Also when it comes to economics and warfare, there are no silver bullets. Just very good guides. WWI broke out mainly because of entangling alliances mixed with a culture of honor (i.e. you don't break your agreements/word).

But look at how WWI ended with Germany getting heaps of crippling debt placed upon them and economic devastation. That totally paved the way for Hitler and WWII. Contrast with the end of WWII where Germany was rebuilt and economically integrated, and today it would be ludicrous to consider Germany invading Europe with designs on the world! The genetics of the people didn't magically change in a couple generations. Their economic situation did, and economic-related needs are at the base of everybody's hierarchy of needs.