Cigarette laws and pharmaceutical conspiracy

And they die earlier, thus you dont pay for their retirement as much -> it actually costs less.

My mother's lung cancer racked up a three million dollar medical bill in six months.
Her cost of living from 65 to 105 would've only been $1.4 million if she were above median income.

Now imagine someone who lives for two or three years fighting it.

Your math is flawed. It also doesn't account for the fact her illness, like many in the US, was due to working in hospitality and being exposed 2nd hand for hours upon hours a day.