[geebee]

True. But do you consider those extra billions to be money he didn't earn in the United States? In this case, it does seem like the US is going after income that was properly earned in the US, it's just that with startups (and IPOs), you can cleverly renounce your citizenship in between the time the work is done and the money is realized.

I see this as different from someone going over to England, working, opening an account, making investments, and discovering that they owe (or at least have to file) with the US.