Bitcoin betting
‘since as a dual-national I can use my non-US passport and not run afoul of any US laws against gaming’
This is not correct, as the United States does not recognize any citizenship but its own (and that pretty much includes those with a Green Card, with the IRS claiming the right to tax their world wide income the same as an American citizen). As a concrete example, an American citizen using a non-U.S. passport to travel to a country like Cuba is still subject to this – ‘Unless authorized by a general or specific license, any person subject to U.S. jurisdiction who engages in any Cuba travel-related transaction violates the Regulations and may be subject to penalties.’