The pie grows larger as people enter the economy who were brought there by the desire to get a free income? I support the proposal, but come on

Definitely true, it's just that people don't know that or want to believe it.

Every attempt at analyzing this for the US economy I have seen concludes that immigration is at best a wash for the people who were already US citizens. It does, however, have the effect of worsening income disparity. Capital benefits while low income wages are driven down. Of course one also has to consider environmental costs.