I had been living in London part-time for 4 years, when I finally decided to take the plunge and make a permanent move ... for LOVE. Yes, for love, the simple thing that makes the world go round. Certainly, with a record number of U.S. citizens renouncing their U.S. citizenship, most people would argue the cause is avoidance of taxes or some other financial benefit. I would argue, even though there may be a financial benefit, the root cause is always love.
Although my love was for a person, whom later became an unrequited love; most expats are living in other countries, because they love their foreign job; they love the foreign country; and eventually they find the love of another. Of course, I have known people who have taken work overseas, because the money was better. However, this is usually a temporary scenario and lasts as long as it takes to find something "better" in the U.S.; or, lasts as long as it takes to become homesick. The people who stay at these overseas jobs for the long-term, end up falling in love with the country; falling in love with the culture; falling in love with the people; falling in love with something...
Realistically, the U.S. has relatively low taxes when compared to other developed countries. Additionally, there are many financial disadvantages to renouncing your U.S. citizenship: higher foreign government taxes; fuel costs are 3 times as much in Europe; and the U.S. charges an exit tax and requires back tax returns, before one can renounce their citizenship. In other words, one must be very certain they "love" their new country, before taking such drastic measures, and must be 100% certain of not changing their mind, because the process is permanent.
Sure, one could argue, if you are making over $155,000 in another country, one will have to pay the U.S. taxes on this excess. But certainly, if you are making a lot of money, isn't it worth spending a little of it on the pleasure of having a U.S. Passport to go back and forth as one desires, and benefit from all the great attributes of the United States? Moreover, the process of renouncing one's citizenship and getting one's U.S. affairs in order is an arduous and confusing one, which will most likely require the "expensive" assistance of financial professionals and attorneys. Additionally, if you are truly making so much money, the exit tax alone could offset any financial benefit.
Many people thought I was crazy, when I left the U.S. for love, and then thought I was pathetic when it turned out to be an unrequited love, and today I may never find the love of another. However, when weighing the financial benefits against the financial disadvantages, I would reiterate my argument: that love is always the motivating factor. Whether it be love of a new country; love of a new culture; love of new people; or love of a career; few people would undertake the complicated and difficult task of renouncing their citizenship, if there was not some love in there somewhere.