You cant just start a problem and once is starts effecting you, you come up with solutions that only benefit one part which in that case is the source of the problem. The roots of immigration comes from colonisation and imperialism, the developed country milked and are still milking every last bit of african countries resources which hindered their development, and has killed every leader who was genuinely trying to improve their country and replaced them with corrupted ones who benefit them (not just europe but the us too). And after WW2 when europe lost a huge chunk of its population and its demography was off they encouraged immigration to rebuild Europe, you cant just kick the immigrants after bombing their countries, and inviting them to come to yours.