system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: My Grandfather, a pack a day smoker for 50 years, died of old age. How do some not die from smoking while others are not so lucky?
gpt
Well he didn't die of "old age" almost certainly.  At least not medically.  There was some other cause of his death listed on a death certificate even if your parents referred to it as old age.

Smoking definitely could have been the cause even if he never got cancer, but like you said, some people get lucky.  Playing Russian Roulette is stupid, and leads to plenty of deaths, that doesn't mean every participate dies from it.