You fail to understand that things other than money matter; how unreasonable are you?
Intangible costs also entail loss of productivity in workplaces, carer costs for ill people and yes DEATH. All these things not only burden people's lives, they actually have consequential DOLLAR costs attached to them as well.
It is the government's job to protect us as a society, providing the most reasonable environment for us all. This should include illegalising a damaging drug like tobacco.
We also pay to treat those who are born with genetic illnesses...
You are overlooking the fact that Genetic illness is not a lifestyle choice. It is misfortune. We can't help it in a way which is readily available to a wide community. It does not contribute significant cost to the population anyway.
...who work in coal mines, who drive dangerously...
Again, both of these things attribute very little to tax costs when compared with tobacco.
...who eat unhealthily, who don't exercise...
I agree. Obese people should have to pay more taxes because of their growing strain on our healthcare.
...smokers do actually pay for the added cost to the system, many times over.
No, they do not.
They pay for one fifth of the costs incurred by tobacco abuse. The other 25 billion is picked up by non-smokers, which is completely unfair.