A couple of points — in the first place, the number of undocumented residents isn’t increasing. It leveled off around 2010 to around 11 million and stayed there, meaning we‘ve reached net zero on illegal immigration, with as many leaving this country as entering. So your argument of it “driving the population to 500 million” has no merit.
In the second place, the wall isn’t going to do much to keep people out. Oh, it will make it a bit more difficult to cross the southern border in places, but there are other ways into the country. There’s the matter of overstaying visas (currently the largest source of illegal immigration). There are tunnels. There’s a Canadian border, which is mostly unguarded. And there’s a great deal of coastline. The coyotes who escort people over the border for a fee? They’re just going to change their business plan to involve boats.
In the third place, study after study has shown that undocumented residents aren’t really damaging labor markets. Farmers have tried to get American citizens to pick their crops in the hot sun. They haven’t had much luck. But if you’re an American citizen and would be willing to go pick crops, I’m sure that any farmer would take you — that is, if you can do the work as well as the workforce they now have.
In the fourth place, you claim that “poor illegals” are a net burden. This isn’t surprising, because “poor” anybody is a net burden. But not everyone who immigrated here illegally is poor. Those who are not contribute as much as everyone else.