<<...that can cost the government huge sums...>>

People have the right to smoke. In fact, I would make the libertarian argument that they have the right to use any drug they wish, privately. That the government places itself in a co-dependent relationship with smokers is another matter. Who, if anyone, should bear the cost of their damaged health is a complex question of responsibility, especially since tobacco is addictive and especially since the government more or less sanctions its marketing to those immortals otherwise known as teenagers.