A succinct and pithy saying, but generally incorrect. Historically, good times create a food surplus. A food surplus creates well-nourished armies. Well-nourished armies, for better or for worse, create hard times for everybody else.

As I've posted elsewhere in this thread, I would recommend reading the following series of blog posts.

https://acoup.blog/2020/01/17/collections-the-fremen-mirage-...

You’re taking it too literally. It’s not about physical strength, it’s about cultural and societal strength and fortitude.

Ah, so it’s a vague unsupported aphorism that purports to explain something unmeasurable?

Just because something is pithy, doesn’t mean it’s true.

Exactly. It was in response to the “America is too comfortable” part of the comment.

Great quote, firm believer in it.

The generation that grew during WWI and post it, gifted us with WWII.

Hard times can create hard ressentful men who value low empathy and are eager to unleash hard times on others.

I agree with OP in some general sense in a closed political ecosystem because WWI/II didn't happen in a closed ecosystem. The extremes were just enough that it couldn't be easily contained within their perspective domains or countries. I wasn't aware of apt analogies before reading this thread but I just called it the Champion's Paradox, that with enough wins a fighter generally becomes less vigilant, "decadent" if you will, and I'd wager that the same holds true for larger domains as well given that all other things being equal.