It has more people than I thought.
Even in our Capitalist system, we have enormous poverty. Some would say do away with the welfare state, and while it sounds good it's never going to happen. Politicians barely have the spine to cut back on the increases. I think at the very least though, we should not give illegal aliens anything but a one-way ticket back home. What would be even worse is if WE were a country of a billion. There's no way we could sustain a population of that size and keep a welfare state.
I'm not against immigration, just that right now it's lacking in common sense. You don't import people while Americans are being laid off, and you DON'T let millions of illegals pour in here with no enforcement.
Then the point is academic, even if you completely closed immigration--our home-grown leeches will sooner or later consume more than the entire American economy COULD produce, no matter how much it was protected, and then we would have two options: demand tribute from every other nation on Earth, and eventually start a global war, or experience an economic collapse.
The welfare state is the root of our problems. It takes from the productive and rewards the unproductive. This has two pernicious effects: it keeps the unproductive in that state because it doesn't give them any incentive to become productive, and it lowers the productivity of those who ARE productive, because they receive less reward than they otherwise would receive for being more productive.