The kalergi plan and the fantasy of great replacement...
Some idiot above us, well paid and unelected as if I needed to specify that, thought he could be replacing or bastardizing the local population, probably a bit too aggressive and resisting his attempts at dominating and taxing them to death, by a more "diverse" sort of people that would be fed on free shit to give them time to outbreed the locals, for it is believed they could either become majority or mix with them, thereby reducing the opposition by means of IQ lowering.
On the paper it may look like the heist of the century, but considering we are dealing with populations of different backgrounds with different abilities, cultures, pursuits and modus operandi, the results are going to be totally off the charts regarding the future value generated by this brilliant idea. As an exhibit, consider existing secular multicultural countries; There is no such thing as a melting pot. Races do not mix that easily. Not at all. If there's one thing you can take to the bank with you, it's this.
So, in addition to being totally subsidized and unproductive, said diversity has also become master in the art of depredating, raping, stealing, and otherwise costing money for no tangible positive economic result. Add to this the fact that these dudes cannot even feed themselves or craft anything useful, and you'll get the idea, which will cost the entire country or group of countries an awful price and bring them loss of prosperity, which in turn will lead to the demise of the once powerful and centralized institution which came up with this genius scheme for lack of tax revenues.
You do not put anyone into submission by giving him infectious diseases or parasites that will come back knocking at your doorstep.
Welcome to idiocracy.
The only sensible reason why would someone come up with such abject failure is that this person would intend to destroy the countries regardless of any other favorable outcome.
And just who would destroy the country he grew up in?