well thats just it. all this emigration we see is a result of the prior colonial expansions and the wars in other continents.
the reason the UK is turning into Northwest Asia is because of Raj. the reason France is turning into Mahgreb North is because of 1800’s colonialism. The reason the US has pockets of Viets, Cambodians, Hmongs, and Somalis is because of our own little wars. These places lose their best minds to EU UK and US, and are left with second tier intellects to run their affairs with the usual predictable results.
Those European powers - and now the US - are paying the price of empire. I left the UK in 1974 after five years and even in those days, the place looked like Quetta.