Saying about the cost of a smokers healthcare compared to how much they suposedlyu cost the healthcare system is only taking into account a small part of the picture.
Do a search for the health costs of a smoker over a lifetime compared to the cost of a non smoker & it's often reported that due to living longer a average non smoker will cost more in the course of their life than a smoker.
It's a simple fact that many smokers don't live until retirement so that's one less cost for the government, this extract is from a Dutch survey done in 2008:
A Dutch study published last year in the Public Library of Science Medicine journal said that health care costs for smokers were about $326,000 from age 20 on, compared to about $417,000 for thin and healthy people.
The reason: The thin, healthy people lived much longer.
It's a sad fact of life that we all die but non smokers tend to have a prolonged period of not contributing to society (retirement) whilst requiring medical/housing/financial support from the state.
Try reading these links for some of the details (I can't get the page with the Dutch research to load but that's the downside of using a PS3)
http://healthland.time.com/2009/08/04/does-prevention-really-cut-health-care-costs/http://usatoday30.usatoday.com/news/health/2009-04-08-fda-tobacco-costs_N.htm