Give or take, about ten generations, and the best men of any nation are winnowed out in wars. After that, it’s all over but the lamentations of the women and the girly men.
And we’re getting there fast. Not enough good men, too many whiny women, nanny state, extended childhoods. :(
That theory is hogwash. There are plenty of good men and good women. The trouble is the barbarians learn how to use our system against us, and we haven’t figured out a way to fight back thats not violent.
I dunno. One could also make the argument that wars also winnow out the weak, stupid and unlucky. I realize that sounds bad, but you can be very brave & patriotic but still have other flaws that contribute to your death. Death is war is also somewhat random (hence the “unlucky” qualifer).
That being said, WWI and WWII were waged on a scale never before seen in human history. I think the loss of Alpha males from that conflict is definitely behind Europe’s decline. WWI likely set back any recovery France was making from the Napoleanic wars.