Anecdotally, I've had 2 experiences with people like that. One was a coder who was self employed and worked out of his house, and another was my auto mechanic before I moved. Both always had a cig burning sitting burning in an ashtray but only picked up and consumed maybe 25% of it while they were working.
In some places, cigs might cost $15/pack (your numbers), but I just passed by a Chevron gas station selling for $7 where I live (Portland, OR). The cost depends greatly on the local/state taxes and is not indicative of everywhere. A carton of Marlboros here (the most expensive brand) is around $60 ($6/pack). A quick scan of this table [1] shows rates by state. A cursory look shows a tax range of about 0.37% (Georgia) to 4.5% (DC), but those are only the state taxes and don't take into account other local taxes. I'm just pointing out your example of $30/day (I assume where you live) is quite different from $12/day where I live, and there are even cheaper places than where I live. Portland isn't exactly the boonies.
[1] https://en.wikipedia.org/wiki/Cigarette_taxes_in_the_United_...