An average Nigerian worker can increase his income almost 15-fold just by moving to the United States, and residents of significantly richer countries like Mexico can more than double their earnings. The humanitarian gains of letting everyone who wants to make that leap do so would be astounding.
If too many people do this, too many come from 3rd world countries to America, then the Nigerian will not be able to increase his income by 15 fold any longer. If we suddenly had hundreds of millions of these people here, they would drag down prevailing wages in American so much, that he might rather stay in Lagos and look for a job there.
It appears that that’s already happening, considering what’s happening to the producers and the middle class in the US.
Now you are getting smart. At that point, we achieve One World Nirvana with our betters in complete charge. < / sarcasm >
It is sadly inevitable that wages (and standard of living) in the US will go down to get closer to the rest of the world. Many rightly rail at the huge debt that the US is accumulating, but the ugly truth is that, if those debt increases were to stop, the standard-of-living would necessarily going down.
Many who rail do not wish to accept that, but it is true.