The population pyramids are there for everyone to check. "Extinction" is strawmanning it though, the case is about living in a society with a shrinking wealth

The population pyramids are there for everyone to check. "Extinction" is strawmanning it though, the case is about living in a society with a shrinking wealth and growing dependency ratio. The expectation is that the average standard of living in such society will fall compared to an era of widespread prosperity.