Looking holistically the person leaving the US (or lets say 100 people to make it easier to see the point) means 1 to 30 less startups and so maybe an entire company or more not being started. That is less revenue for US.
What most people from the "they steal our jobs" mentality (not saying that is you, but this a seperate point) don't get is productive people create jobs by being a customer of many businesses.
That doesn't mean your plumber isn't qualified—just that people looking for webapps want to hire workers who know how to make them.
There is the other side plenty of workers successful at programming language could be trained to fill any gap. That's what happened in the 50s and 60s..
PS The number of roles that there aren't qualified Americans for could be counted on one hand. This has always been about reducing salaries, not shortages.
Of course I am exaggerating, but this is not a 1 dimensional problem.
This is why in the modern world some sectors are always crying about "worker shortages" while asking always more migrant workers to come in - salaries are compressed as a result, and locals have no incentives to enter the branch.
Hence importing workers may be useful for needs that are limited in time and space (say, install a specialized foreign machinery in a power plant), but systematic importation leads to dequalification of the local workers, who flee the branch that has now low salaries.
This might be less true if there is resource starvation but we have transport and imports and exports. You can accomodate more people and feed them.
>The facts show that just like the amount of labor is not fixed, neither is the size of the economy (fixed pie fallacy) and as more work is done, the economy grows
Your reply is a glib thought-terminating cliche strawman that doesn't address their point at all. Interesting!
Besides, yeah, if you hire people who will work for any salary, the amount of jobs will increase, but salaries will decrease, for locals as well. After some time, locals will flee sectors where the migrant workers are brought in, creating further self-inflicted "labor shortages"...requiring more migrants!
The main winners are capital owners, who, thanks to the migrant workers, can now acquire a larger part of the added value generated by workers.
Yes the job market exists.
I feel like the better argument is that the greencard holder was the best candidate and thus will be more productive in the role. It is just efficient resource allocation. That, even without new companies, will drive profit/expansion/more jobs