I am a trained economist, and from what I have read illegals are probably a net loss because they take up more in government benefits than they contribute. Most violent crimes west of the Mississippi are committed by illegals.
America imports its poverty. Immigrants are the poorest group of Americans. Asians contribute to the economy quickly. Mexicans do not. it is hard to make a generalization about them.
Immigrants do not bring wealth to America, whereas Americans normally have wealth accumulated.