If you are in a bar which allows smoking, then you have intentionally gone to a smoke-filled area. The smoke-filled area has not come to you. Nobody invaded anything around you.
What dazzling logic, not! I remember when smoking was allowed everywhere. Airplanes, buses, trains, restaurants, restrooms, everywhere except fuel depots and explosives factories. By your logic, in those days my wanting to eat out, take a plane, train or bus trip, or even just go to the bathroom meant that I chose to go into a smoke-filled area, so it's my own fault. The only reason there are non-smoking areas now it government intervention because smokers felt entitled to smoke everywhere no matter what. More than 60% of the US adult population doesn't smoke so why is it that the 30 some percent think the majority should stuff it.
Smokers should only smoke if nobody within breathing distance minds (~30 feet). If anyone minds, then don't smoke. I sorry to hear that you are addicted to nicotine and I hope you don't die of lung cancer but you have no moral right to continue to smoke in the presence of non-smokers.