I expatriated 9 years ago. As a US citizen living abroad you do not have to pay taxes on the first $85K in income earned outside the US, so long as you do not reside within the US for more than 45 days per year.

In the country I live (Costa Rica), we are not taxed on income earned outside of CR. I earn a living playing poker online and legally pay no taxes.

If you wish to renounce your US citizenship, you must first obtain citizenship in another country. This isn't as easy as you might think. Once you renounce your citizenship you are still liable to pay taxes to the US for 10 years. (like it or not, you are the property of the US government). There really is no incentive to renounce your citizenship as you can become a resident or even a citizen of another country and maintain dual citizenship.

As far as the pokerrooms that don't allow US players being softer, from reading the posts by foreign players on various forums, they all complain that the sites have become harder now that the US players are gone