It's an increasingly hard world for those seeking a better life in richer countries. Immigrants aren't welcome in most states, even where demographic trends reflect the need to expand the labor force to levels able to sustain and support aging populations.
While both Europe and the United States will have to face the need for younger workers in the coming decades, citizens in the wealthy nations, no matter what their ethnic backgrounds, dislike mass immigration and punish politicians who allow it.
In Europe especially, immigration is the main driving force for nationalism, for the rise of populist parties and for the decline of the center left.