[cynicalkane]

To a multibillionaire, the value of retaining American citizenship could easily be hundreds of millions of dollars. Or it might be much lower in that. The degree of which citizens seek tax havens will be proportional to the level of taxation, not a black-and-white yes-or-no thing.

[liber8]

I would argue the opposite. To someone with several billion dollars, citizenship probably doesn't matter all that much.

To someone with a couple million dollars, having that U.S. flag on their passport does afford a great deal of freedom and security. But, with several billion, you can pretty much buy all the freedom and security you can get.

[grandalf]

For a rich person the costs of moving (and other transaction costs) are far less... arguably if the transaction costs were lower (walk across the border to a waiting job) lots more people would do it at far lower income/tax levels.