Mexico has an extremely high birth rate --- and while a generation for Americans is about 30 years, it's about 15 years over there --- our population doubled in the last 50 years and much of that doubling was from immigration from Mexico. We can't keep absorbing impoverished people at the rates we've been seeing.
You could be right. But I'm still not in favor of militarizing the border or any of the other unconstitutional proposals I've seen so far on this forum.