Anyone who has traveled, especially to a war zone, knows that America is the world's beacon of hope, freedom, and opportunity.
Millions of people the world over know it, too. That's why they try to come to America every year: They know a good thing when they see it.
But unfortunately, far too many Americans don't know when they've got it good. Life in the USA is pretty sweet, actually, and given all that is wrong with many of the world's countries, even our flaws seem pretty damned petty by comparison.
That said, our country isn't a Soviet-style gulag. There isn't anyone preventing anyone else from finding relocating if they just don't think 'Merica is good enough or moral enough or righteous enough for them.
Like the old saying goes: "Don't go away mad, just go away." You're free to leave.