You're extrapolating linearly. Earth's population has doubled since the 60s - and the technological civilization worked reasonably well in the 60s. It's not necessary to have many people. You need the right kind of people.

What would fewer people mean? Housing demand falls making it more affordable. At the same time people's pay would go up. All this would likely lead to a stabilization of birth rates.

But if ((elites)) flood White nations with dumb and criminal aliens this process can't work and what you'll get is chaos and collapse.