I understand your reasoning an, on a flat surface, would agree with you. But realistically, we are not going to be able to shut down immigration entirely, and I think it would be better, in the long run, to allow in more skilled, educated people. Right now we are importing the ignorant, poverty stricken losers of the world, and paying, one way or the other, to subsidize their presence here. Skilled workers would at least be self-sufficient.
My father was one of those poverty stricken losers who came here from Ireland in 1929. He served in WW2 and received no government subsidy beyond social security and VA benefits. Most people who come here are not rolling in the dough back home or they wouldn’t come. That’s most not all.
The bulk of this country is made up of the descendants of poverty stricken losers. The difference is they were looking for a step up not a hand out.