The predictable perils of illegal immigration: they come from refusing to look at the predictable consequences of your actions. Your actions. We decide in a reasonable and hopefully wise way how many legal immigrants can be accommodated, and from which countries. How many jobs will they need? Where are they likely to go, and what will that mean for the schools and hospitals there? The number waiting at the door is ten times the number we admit, and if we admitted that entire group it might spark even more getting hopefully in line.
Then people come in on top of that, illegals or refugees we hadn't counted on. I imagine those who try to map out how many legal immigrants we will accept take some estimate of how many illegals will come and try to factor that in. Refugee numbers are harder to predict, but we can take an average, or look at the world hotspots and guess. I don't know how well these assigners and predictors do their job, but we have commissioned them to do exactly this, so I am not objecting to whatever numbers they come up with.
In good times we plod along pretty well, making a little more room at the table for the unplanned-for immigrants. Then hard times come, like a recession or a pandemic, and all of a sudden those illegals are like the penguins at the edge of the ice floe about to be crowded off. There is no room for them and they get evicted or don't qualify for programs that don't have money left over for extra recipients, or they can't get the black market/gray market jobs they used to.
People of compassion throw up their hands and holler and say "Oh no, these poor people are being evicted. They have food insecurity and some are even going hungry. Their children can't get any special help at school or the right medical care." And the Gods of the Copybook Headings say "This is exactly what we told you would happen, but you are again surprised. You caused it."
Looking at problems and emergencies as if they came out of nowhere and the proposed solutions will have no downstream effects is a method for creating more problems and perpetually feeling sad because of suffering.