Reproduction always wins, in the long-run, over non-reproduction, regardless of the unsavory other traits which may be associated with particular bands of fecund individuals.
When your people become too smart and sophisticated for having children, you die off.
Meanwhile, less sophisticated people are reproducing rapidly. And there probably will come a time in their future when many of them will be killed off. But that’s okay, because there will be a lot of smart ones surviving, and their survival prowess will then be evident to their potential mates.
The people who found children too tedious, as a whole, will have been marginalized by then.
I wish nature had better taste, but nature really, really doesn’t care.