Making the US utterly isolationist, destroying our economy.
Says who? That is the fallacy of false dichotomy - either isolationism or de facto unrestricted immigration (which we have now pretty much).
Few people support closing US off from immigration. But immigration needs to be legal and based on good policies. Illegal immigration or bogus asylum seekers are not necessary to have a good economy.
The right goes on and on ad nauseum about the border and the wall.
1) His Flatulence's wall doesn't work, although it does make it a bit more dangerous. (Falls while crossing the wall. Expensive for the nearby trauma centers.)
Walls, or physical barriers, can work. Of course, physical barriers can be overcome. The point should not be to prevent crossing, but to slow illegals down so they can be apprehended. I.e. you need physical barriers that are monitored and patrolled.
Of course, all that is nullified if you have stupid laws that say that if an illegal is caught, all he has to do is say "asylum" and he gets to stay anyway, for years.
2) It's just the border is easy enough to cross--if you did manage to seal it you would just cause them to come by boat.
Which makes it more difficult. The more easy you make it, the more decide it's worth a try. So making illegal crossings more difficult is a good goal.
What should also happen is to make it more difficult to do things like work or find a place to live if you are illegal. That will also reduce the inward pressure and may even cause many to "self-deport".
There are ways to improve the situation. Unfortunately many on the Left want more illegals to come to the US, not fewer, and so they do not want to fix the problem, but to break it even more.