>First, more people means more outliers—more super-intelligent, super-creative, or super-talented people, to produce great art, architecture, music, philosophy, science, and inventions.
There might be 1,000 certified geniuses per billion, but we are still slaves to probability. That genius might be born in the slums of Calcutta or in the middle of the Amazon rainforest or in the vastness of the Mongolian steppes. I guess the hope would be that 3 or 4 might have the luck to be born to a middle class or higher family in the first world.
Also, whatever this dude wants, the world is in major decline. For example, because of China's one child policy, their population will be halved in 50 or 70 years and nothing can stop that. Japan has a high over 40 population, Italy, Germany, Spain, and especially South Korea. Russia has been declining in population and with the war, the best and brightest have left Russia, never to return (they are devoloping lives, wives, children wherever they are now), and the meat grinder of the war. Same with Ukraine.
The same thing happened in ancient Rome as well. It got so expensive to raise a child in Rome (yes, inflation existed back then as well), because of money pouring into the administrative city of Rome - for the same reason now in the first world, that people stopped having children. Even back then they had rudimentary birth control. The Roman Emperors gave all kinds of incentives for families to have children - grants and tax reductions, but it was not enough.