First, because everyplace but Africa is at the point where birth rates decline.  And Africa faces the scourge of AIDS that often takes people at the height of their working years.

The issue is that if pay in a producing country isn't enough to buy a product, then you have to find someone else to buy it.  Who?

If demand in advanced countries declines with the population, then who buys the stuff.

FYI, I've got a copy of Veblen on my desk in front of me waiting to be read when I go eat.  I just finished Freakonomics.  I was not impressed.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg