Yup. Or: people who have decent jobs and are conscientious about them are more likely to decide to drink coffee daily to make themselves more productive, and these traits also make them more likely to (a) be more conscientious about their health, (b) have health insurance and be more able to pay medical bills.
I don't have numbers on this, but I have the impression that many people drink coffee on weekdays in order to be awake for their job—and they probably wouldn't make it a daily thing if they didn't have a job—and therefore daily coffee drinkers will contain a much higher proportion of people who are healthy enough to hold down a job.
I don't have numbers on this, but I have the impression that many people drink coffee on weekdays in order to be awake for their job—and they probably wouldn't make it a daily thing if they didn't have a job—and therefore daily coffee drinkers will contain a much higher proportion of people who are healthy enough to hold down a job.