The poor have few luxuries. Smokes are among them. I know, it makes no economic sense, but it is what it is.
From a lot of reading about concentration camps of the 20th Century, the last three non-essentials which people will give up are in order:
1) alcohol
2) caffeine
3) nicotine - the last to go.
I don’t smoke. But if I was in a concentration camp and couldn’t get a drink, couldn’t get anything to read, couldn’t chitchat with a woman...I would probably want a cigarette.