How they do it is probably more than we want to know, really. Why seems to me to be that the world's consumers (not just USA) are trying their best to survive in a struggling world economy, while still having "stuff". If everyone in the world who supports this type of economy gave up having every new gadget that comes around, things would change. People seem to accept throw-away goods, and reckon that since the price seems "cheap", it makes up for it. After all, what exits now that won't be "obsolete" in 6 months?
As long as people are willing to buy inferior goods, people will find ways to buy them for resale at prices that allow for profit. That's the Capitalist way. It's a downward spiral, to a point where people simply decide they are really wasting money. Then the push will come for higher quality, and not everyone can or will be able to buy. The haves and have-nots will distinguish themselves. Only when people stop buying cheap goods, for whatever reason, will this cycle be broken. I'm not thinking it will end soon.