All the migratory traffic in the world started after WWII when the European empires gave up their colonies because they “deserved” their freedom. Now that they have it, they want to be supported by their former owners or move in with their former slave masters. You can’t please them, can you?
Never mind colonies, here in the US we have the Welfarian Resettlement Program (aka “Section 8”) to match non-contributing populations with taxpaying hosts. Too many unassimilated minorities in this country function exactly as they would in their home countries, and are spared any consequences by massive injections of taxpayer cash.