It's simple: the US economy is huge. It's bigger than Japan, Germany, France, Brazil, and the UK combined. It's got the same GDP as the EU and as China, but hal

It's simple: the US economy is huge. It's bigger than Japan, Germany, France, Brazil, and the UK combined. It's got the same GDP as the EU and as China, but half the population (and 1/4, respectively). No matter where you are, the US can be a step up -- as is indicated by the OP. These are exactly the immigrants you're asking about, and they came for a shot at exactly this, which they couldn't get back at home. Incidentally, here's a cool infographic: http://graphics.wsj.com/global-growth/ http://graphics.wsj.com/global-growth/