There's a difference between opposing the actions of your country, playing corporate tax games, trying to change things, and a whole range of other activity, and--- explicitly renouncing your nation. Bill Gates has never held up his right hand and under oath renounced America. Most Americans wouldn't either, not even very wealthy, very libertarian ones.
I certainly agree with this, but you also have to account for the fact that it's an incredibly, incredibly bad idea to renounce citizenship when you only have citizenship in one country. If you run afoul of the law in a country you're not a citizen of, even for trivial things, you can easily end up in jail in permanent limbo when they try to deport you to your native country.
In most countries it's very difficult to obtain citizenship for a foreigner. Other countries simply forbid dual citizenships, and treat an oath of citizenship in a second country as a de facto renunciation of citizenship in the first country.
Saverin held dual citizenships, one U.S. and one Brazilian. Now he only has Brazilian citizenship. I believe Bill Gates, Steve Jobs, and Mark Zuckerberg only have (had) U.S. citizenships. It's simply not an option for most "wealthy libertarians" to renounce citizenship.