I think the hyperbole in your comment is clouding your point, which appears to be that you are skeptical that immigration restrictionism is on balance good for the United States, to which I’d say that immigration restrictionism is actually the default setting and the current era of high immigration is unprecedented and new. This is the same pattern in Europe as well. The US achieved its super power status during one of the more restrictionist periods for immigration in its history, so I don’t follow how moderating immigration just a little bit equates to “throwing it away”.