There also one more thing to add here: H1B workers also contribute to Social Security and Medicare taxes and most of them do not get those back because they leave.
How did this get posted twice? I thought HN catches the same URL being posted again
<a href="http://news.ycombinator.com/item?id=2294268" rel="nofollow">http://news.ycombinator.com/item?id=2294268</a>