So if this were actually true about populations then we wouldn't be seeing a collapse of various ethnically homogeneous groups around the planet.

Japan, Poland and South Korea aren't particularly friendly to mass immigration and culturally view imports as permanent outsiders resulting in a high degree of homogeneity among the population.
You're telling me all these countries are seeing collapsing populations, simply because they hold some form of moral system above the survival of their ethnic groups?
Sorry but I think it's more complicated than that and I really don't think you've proven anything other than you're a one-track thinker.