It's a metaphor, "strong" and "weak" refers to the ability to overcome the "hard times", whatever that may be.

Basically if you experienced the direct consequences of a "hard time" (a demagogue, a famine, a recession or financial crisis, SCRUM, or whatever) you will be more aware and resilient to allowing the things that caused that to happen than if you never experienced it. That's "strength".

It is of course true, we see it everywhere in nature, but it's perhaps often more due to hard times eliminating weakness than actually creating strength.

Good times tend to increase the number of people who don't know how serious bad times can get, don't realize the importance of principles that were obvious to the people who survived the bad times.

So "strong people" can perhaps be "created" equally in good times as well, but they are increasingly outnumbered. During hard times the "weak" are eliminated.

This being Ycombinator one can consider the example of how any crazy idea gets funding during good times but during hard times the ideas that actually have legs remain. ;-)

> This being Ycombinator one can consider the example of how any crazy idea gets funding during good times but during hard times the ideas that actually have legs remain. ;-)

Remember economics isn't a morality play where bad things are secretly good. The general principle is that a bad economy only has bad results and there's no reason to want one.

https://eml.berkeley.edu/~enakamura/papers/plucking.pdf