You're asking an extremely broad question with, depending on the context, many different answers. To be broad, you had multiple answers to the questions posed by economics, some of which involve the US taking very authoritarian stances provided it's not within the US's own borders. WW2 and the events leading up to it can be framed as the logical conclusion to colonialism. You really can't not talk about mid - late 20th century south and central American politics without mentioning the US and the CIA, and so on.

Your statement isn't inaccurate, but I'd say its a bit soft? It's extremely easy to look at an entire century and make a broad statement, but what might motivate Germany to get swept up into Nazism or the Russian Empire to go Soviet would be nuanced and different from what cause Guatemala shift in politics in the 50's.

Could you be more specific?