This is what I like to call the Post-Reaganite/Thatcherite Ruin Loop, it was born in the first world and now plagues all of it, but has spread well beyond that now with many ex-2nd-world and third-world countries having entered it at this point. It goes like this:
1. Hollow out the economy by transferring hefty chunks of wealth from the lower and middle classes to the rich.
2. When people inevitably have less kids due to their good education and access to birth control combined with lack of resources to raise children (reduced in step 1), complain about it and point out that it's bad for the economy.
3. To satisfy capital's desire for unsustainably cheap labor, bring in fresh suckers from poorer countries who aren't up to date on how much shittier things became in Step 1.
4. GOTO 1
Any society with a capitalist economy will be fighting endlessly repeating battles to keep from entering this loop, and given enough time having to fight, it will eventually lose one of those battles, and that's all it takes.