So you agree with your friends that people act in their best interests, including changing citizenship, when it comes to taxes, you just disagree on the amount of money it would take?
I don't think it's true for the vast majority of people. Most Americans, including most wealthy Americans, are happy to be Americans, even if they aren't happy about everything in the US. Rejecting your home country for monetary reasons is a fairly drastic action, and only a very small number of people take it. I mean, you don't see Bill Gates moving to Monaco or anything. Not even very-rich people with libertarian politics, like Larry Ellison or the Koch brothers, are itchin' to leave the country.
In fact the number is even smaller than the raw number of renunciations. A spot-check at the list of renunciations suggests that most are actually people who in practice ceased to be Americans long ago, or in some cases never were. Some were born overseas to American parents and have never lived in the US; one actor on the list is of Italian origin and moved back to Italy 40 years ago; etc. Apart from a tiny handful of cases, it seems more like formalizing situations that already exist (people who aren't really Americans just making it formal). A number are also people applying for citizenships in countries that don't recognize dual citizenship, who are required to renounce their American citizenship to do so.
