What's absurd is educated, intelligent people with a knowledge of history fulminating about human nature. No, not the desire of the world's poor to emigrate to more economically developed regions, but the corrupting influence immigration has on politics and business.
Immigration, legal & illegal, is as natural as (solar) global warming. It has always taken place throughout human history, through the rise & fall of civilizations, and it will continue to always take place.
Opposing illegal immigration is purely defensive; we should reprise manifest destiny by considering how to annex Mexico's 38 states.
If the US were to annex Mexico, we would be far worse off. Incorporating third world countries into the US would cost us more than it is worth.