tl;dr US territories often times have the ability from Congress to create parallel tax systems. Some have made attractive ones.

protip: Some other US territories have favorable tax laws too, if you want to dig. Its nice that they aren't being written about by EVERYONE right now.

Nobody's going to spoil it for you because that'll be spoiling it for themselves too.

ALL US territories have the same catch: they are underdeveloped bad neighborhoods, and changing the laws doesn't get the comfortable New England elites to move from their gated communities. New money MIGHT be interested.