Cultural Degeneration

Many lifestyles lead to non-reproductive dead-ends: excluding reproduction or replacing it with simulacrum activity.
Any anti-reproductive trait should lead to its own extinction - at least in theory. Why these anti-reproductive traits emerge and why they persist in the world?

Civilization and IQ above 80 is not sustainable, because it leads people to do things like casual sex without reproduction or programming computers without reproduction.

Humanity will either revert to the hunter-gatherer ape steady state or go extinct.

That's just the way the cookie crumbles, deal with it.