All the things you mentioned we in the Overpopulation Project report about how Japan has been faring since it has lost a large number of people. The country is also noted (wrongly) that their 'racism' has kept them from acquiring more people through immigration. The one thing on the rise in Japan is energy use due to the use of machines as robots.

The huge problem with our 'cornucopian' based economists is they are loath to change habits. It was shown the first new VW bug model almost didn't get made as the industry thought such a change would fail and cause the industry to crash. We all know how this has now created a trend. The thing that cost VW a huge price was their deceit in the pollution levels from their cars. When the Roman empire was crashing, due to the governments inability to manage and serve a large number of people coming into Rome from the outlying areas, there was a loss in Roman citizens and, of course the government tried to push the citizens to have more kids. After 2,000+ years we still haven't learned.

What economist fail to understand this planet has a set resource base and every area has a carrying capacity. People, as Musk feel we can send the 'excess' population into space and even colonize Mars. He seems to be devoid of understanding even basic math.