You are correct. You will notice that my comment was only meant to address "one thing in particular" about what he wrote, and I referred to the rest as "vague h

You are correct. You will notice that my comment was only meant to address "one thing in particular" about what he wrote, and I referred to the rest as "vague hand-waving". The issue you bring up fell into the latter category. In 2018 immigrants made up about 17% of the labor force in America. These jobs are primarily the sort of thing you mention: services, agriculture, lower-end industrial and manufacturing. These jobs occupy the low end of the earnings spectrum. If there are no more immigrants then they will be filled by Americans or not at all. So, say we close the borders. Eventually everyone doing these jobs is an American, i.e. born here. Maybe they are making a little bit more than the immigrants who held these jobs before, because there is a new constraint on the labor supply. In an instantaneous view, some of these jobs will disappear because they no longer make economic sense with the increased cost of labor. So what have we changed? These people will not be big earners. In today's America they would not "prosper". Overall wages do not "skyrocket". We have moved the needle, sure—we've made a real change. Realistically, what second-order effects can we expect to see? This is not an easy question. The "lesson" is not "clear". GGP, whatever fragments of truth may appear in his comment, is full of shit, and pointing that out is why I posted.