Those 3 people raise the standard of living. I doubt that when those three people take a job they ask for less money to feed their families as the cost of an American working in a job. That is not always the case.
That storefront in some neighborhoods will still be a storefront if it is American-owned. The idea someone has to come here to do that is not equal to three people winning Nobel prizes.
Yes, immigrants raise the standard of living.
Yes, immigrants lower the standard of living for those who just need a good-paying job.
Depends on your relationship with the economy.
BTW figure out how many immigrants when declaring their income $haft the tax man depending on their industry.