Immigration doesn't reduce wages. But for the people who want to stop immigration, the facts don't matter. Halting immigration is an end in and of itself, and they will reach for whatever justification they can in order to justify that end.
The other justification people will reach for is "immigration is bad for the environment". Basically, the Trump people won, and succeeded in making even liberals and leftists wary of immigration, and everyone is looking for a theoretical reason to pause it.
I've been saying this for a year or so now -- The pro-immigration side has lost, despite the polls showing increased support for immigration. Trump and Miller won. Immigration will bounce back a bit under Biden, but the recent era of openness is now over.
2/A few people claim that Scrooge would put $600 to better use, because he'd save the money, which would increase investment, which would make society richer, instead of consuming in the present.