This is what I think is happening, on a large scale.
I have been watching a lot of Peter Zeihan videos lately. He, correctly I think, is pointing out how demography is dooming a lot of western countries, the US included. When countries get wealthy, they don't have kids at the same rate as when their country is poorer and agrarian. Western globalism is largely dependent upon the consumption habits of 30 year olds. I believe this is largely correct.
I think our globalist leaders have concluded that the way to stave off economic failure is to import a working consumer class. Zeihan says our problem is that it takes three decades to grow a population of 30 years old men and women.
The problem is that you cannot integrate an immigrant population in a welfare state. It worked in the US before 1920 because there was no welfare. What people don't understand is that fully one-third of all immigrants to the US in the great migration WENT HOME. They couldn't cut it, and didn't like to work. So they went home. That left us with an independent and motivated population.
Our current welfare state inverts that mechanism. We will get the unmotivated and dependent people of the world. It will cause our collapse, all in the name of preserving demographics.