re: If you were offered a million dollars

Your friend should look at Puerto Rico. No federal capital gains tax. You could take that $1 mil and put it in a low-cost index fund returning 10% per year. In Puerto Rico, you'd get to keep all $100k, whereas in pretty much any other state/territory you'd only get to keep $80k.

I think the catch is that you have to own property and spend most of your time there. Like, you have to be an actual resident.