Why not just decide that only white people or only men or only people born on Tuesdays can apply for the job you want?

The job should go to the most qualified person. That's how america works. If that most qualified person is actually a guy who was born in india, great. I have no problem with that. You don't get to bogart opportunity based one what zip code you were born in.

What is the purpose of a nation if not to benefit its own Citizens. If it doesn't do that in good times then why would anyone fight when called upon?

...Do you think the point of the United States of America is to help you get a job that a brown person is better qualified for?

What are you even talking about?

The point of the United States of America is to take care of its citizens. A "better qualified brown person" has their own country where they can apply for jobs without any restrictions. Them coming to US is a privilege, not a right. And I say it as H-1B visa holder from Europe.

Would that US citizen be even better off if we got rid of all the other Americans so they had to compete against nobody?

Immigrants contribute to both supply and demand. It's not at all obvious whether this is net good or bad for natives' pay.