Someone who lives in a tax haven to avoid taxes in other countries. Someone who lives their life according to their hone country (U.S.) and international tax law to circumvent high income and investment capital gains taxation. Generally speaking these are almost exclusively millionaires super millionaires and billionaires.
Examples
Richard Branson
John Paulson
Peter Schiff
Nomad Capitalist
That guy is a tax havenist living in Bermuda.