Probably people who will come will need schools and social support. They will need a social infrastructure. They will need more housing. They will need more teachers, etc.
We can see it now with the six million Ukrainians who have fled to Europe. The European social systems and their public services are overloaded by Ukrainians because Ukrainian kids have to go to school and to hospitals. You need teachers and doctors who are fluent in Ukrainian because otherwise you cannot teach Ukrainian kids. They don't speak Polish or the German language.
There are many other things in Europe. Yes, Europe has done very well with the six million. It was unexpected that they actually absorbed the people and are dealing with the six million Ukrainians who fled the war, but if 10 million or 15 million Africans or Asians come to Europe, for example, or to North America, you will need to provide these people with basic social needs and public services. You cannot just put them into the streets.
That will burden the social system.