Does the US tax law provide an economic incentive for its wealthier citizens to expatriate?

Assume that 1) a person has several million dollars and wants to retire, 2) they probably have 30 years left to live, 3) their investment style is such that the majority of their future income would come from long-term capital gains. Given these assumptions, wouldn't it make sense for that person to acquire citizenship in a country that has no capital gains taxes (e.g. Switzerland, New Zealand, etc) and renounce their US citizenship? Without capital gains taxes, assuming a 9% annual return, each unspent $1m would grow to $1m x (1 +9%)^30 or $13.27m in 30 years. With a 25% cap gains tax, each million would only grow to (1 + 9%(1 - 25%))^30 or $7.10m. It seems to me that such an individual would gain another 87% (13.27 / 7.10 - 1) in long-term investment earnings simply by changing their citizenship. If this is true, it would seem to provide wealthier US citizens a compelling reason to take their money elsewhere which would hurt the US economy in relative terms. Is this correct?

The present Federal capital gain rate is 15%. However one who found a country they would be willing to live in could avoid that by the expatriate process. Since there have not been droves of people doing that I would think that other factors may play a major role in those decisions.

The rate you our using is incorrect (at the moment), but you make a good point. Please keep that in mind when choosing who to vote for. Those who support 'repealing tax cuts for the rich' don't want the voters to consider that possibility.

I doubt anyone would renounce US citizenship solely for tax purposes, but taxes could by the proverbial straw that broke the camel's back.