This book is Idiocracy, the book. pendell argues that civilization self-destruct when less capable / energetic members of society outbreed those who are. What does he actually mean by capable? Well, the conclusion might surprise you but it all comes down to morality. shitty people make more shitty people and those numerous shitty people ruin everything just by being shitty. The author was a huge proponent of eugenics which he saw as a radical but necessary move to ensure our current civ doesnt commit suicide. One of David Dukes favorites!

https://www.colchestercollection.com/titles/pdf/W/why-civilizations-self-destruct.pdf