Trump himself is a descendant of immigrants. Why does he oppose immigration?

In the United States, except Indians, all are descendants of immigrants. Although the national policy of the United States has been open to immigrants for a long time, among the descendants of immigrants of all colors, there are also many people who oppose the continued open immigration policy. Trump is just an extreme representative. Personally, this has a lot to do with the economic downturn in the United States in recent years. Many people are afraid that the national welfare will be worse after the influx of new immigrants. For example, if a dog occupies a piece of land, it may not welcome other dogs to come again, even though the land is not its own. ...