Demography vs. Economic Growth

[william the wie]

Japan, Russia, Germany, China, the Asian tigers and to much lesser extent India are all on the glidepath to zero population not just zero population growth. Their economic growth is great but at the cost of population growth meaning that they eventually will become somebody's colony, maybe of the US maybe somebody else's colony, but definitely their political future is bleak. So why do so many threads advocate that the US be like them?

Serious question.