Someone just learned that if you move out of the U.S. and formally, legally renounce your U.S. citizenship, that means you become a non-citizen. And when you're a non-citizen, no matter what your previous citizenship or how much money you made from Bitcoin, you have to go through the visa process when you want to enter the U.S. D'oh!
Roger Ver is a citizen of Saint Kitts and Nevis since he said the magic words, paid the fee, and turned in his passport a little under a year ago. Which made him a non-citizen, period. Did he think that being born in the U.S. would put him in some kind of special category of non-citizenship? Sorry, dude. Every non-citizen who wants to enter the U.S. for a short trip like the one Ver contemplated must apply for a B-1 or B-2 visa, and the government can pretty much turn you down whenever it wants to, for whatever reason it wants to.
This is one of the prices you pay when you choose to renounce your U.S. citizenship. Bizarrely, it means you choose to be treated the way the U.S. treats everyone else in the world who isn't a U.S. citizen. What a maroon.