I was referring to economics, yes, but what you said has no empirical support.
And you know, the immigrants...
There have been lots of studies on the issue of immigration, the workforce and economics.
However the main conclusions seem to be that while immigration is a slight positive for the economy (and obviously for the immigrants themselves) it is a negative for the "native working class", whose jobs get taken over by immigrants earning less in many cases.
The (native) rich and priviledged, and even the upper middle class profit from immigration, but the (native) working class does not.
"Lump of Labour" might be a phallacy but there is
some truth to the usual "immigrants taking our jobs!" line
I would also add that in my view, when unemployment is low if you artificially reduce the supply of labor by restricting immigration you will end up forcing companies to pay more for their employees, increasing wages and taking people out of poverty. Now, there are limits to this (Labor shortages can be a real thing) but the general principle is true.
Similarly, when unemployment is high, if immigrants take the jobs of those who are unemployed, it is harder to reduce unemployment. Similar principle to above applies.
TL;DR: Immigration is bad for the (native) working class, even when it is beneficial for the economy at-large