Eh, I liked it for explaining how people can behave differently.
It doesn’t have much predictive power, and thus is bad science, but I like its descriptive power. I also think it’s a bad idea to see it as a quaterny (binary, trinery, …) instead of a spectrum. Same with being introverted/extraverted - that’s a spectrum as well, IMO.
I think it has more to do with the baby boom right after 1945. If those older people retire, there isn’t enough younger generation to support them, so more people need to work longer, so we don’t get too many retired people all at once.
I think it’s more of a “can we support the retired” kind of issue - not just “muh money”. It’s a little more nuanced than that.