Like, if you had to personally host an economic migrant from a very poor country I don’t think your resolve would hold.
It's your assumption, I've hosted two people from a very poor country (Ukraine), not for too long (3 months) but we had no issues. But it's just one, my case, anegdotic fact. Also, I personally know many refugees, I've helped some to get through the border, who were determined to find new life in a new place and they succeeded. However I know and have that in mind, that not everybody acclimatize and some need really wide and huuuuge spectrum of help and guidance

Also, we have to finally understand that global climate changes will make tens of millions people to move from their, already unhabitable areas. Whatever numbers of people moved already, it's nothing compared to the near future. We have to be prepared for it, but not with guns, bullets and walls. We have to prepare them, to export knowledge, education, culture, financial help to poor countries to that there won't be that huge schock for both us and them during upcoming migrations.

And yes, I don't care bout artificial borders. Even biblical (other religions for sure speak the same) Natural Law talks about it. Nature doesn't belong to any person. Land doesn't belong to any person.