You left out the context. It's not an issue at an individual level. I very explicitly stated that I was talking about societal level.

That means that the society is worse of if everyone does it

And importing goods is a good example why the scale matters. People usually import items worth maybe some small fraction of their yearly income, whereas some immigrants are known to sent back more then they spent locally.

Which is fine if they're actually world class talent, because then there will be very few people doing so, and their intellectual contributions likely offset any other issues. However, as you scale up the immigration percentage, it eventually does become a societal problem.

And the governments job is explicitly to look at the well being if the society - at least ideally. How much they actually do (vs just trying to siphon as much tax payer money as they can get away with) is another question I'm unqualified to say wrt the USA