They do contribute to society, and they do useful things. This is evidenced by the fact they are still in business and their customers still give them money.

Now granted they may not benefit -you- directly, they may even make -your- life worse, but -society- as a whole keeps them around.

Personally I'm not a smoker, so cigarette companies (to me) are a net loss. On the other hand enough people see them as a gain so I bow to societies vote.