As this was where you made you question, I'll stick with you here in the ruthlessly utilitarian minefield (i.e. people and $$$'s are fungible).
First, a clarification, it's 30 pack-years. There are lots of ways to get to that number. 30 years @ 1 pack/day and 15 years @ 2 packs a day are both 30 pack-years. That number sticks with you even if you quit 20 years ago.
So, especially for the younger end of that range (55yo), people between 55-65 are often in their peak earning years (finally gotten seniority or management) and this is when they are most often finally paying off their debts (mortgage, etc). It's also when they are likely doing peak elder care and also sending their kids to college. So this is the time where they are probably doing their peak economic and social good. If you can catch something that keeps them productive for an additional 10ish years, you've probably come out ahead for it.
First, a clarification, it's 30 pack-years. There are lots of ways to get to that number. 30 years @ 1 pack/day and 15 years @ 2 packs a day are both 30 pack-years. That number sticks with you even if you quit 20 years ago.
So, especially for the younger end of that range (55yo), people between 55-65 are often in their peak earning years (finally gotten seniority or management) and this is when they are most often finally paying off their debts (mortgage, etc). It's also when they are likely doing peak elder care and also sending their kids to college. So this is the time where they are probably doing their peak economic and social good. If you can catch something that keeps them productive for an additional 10ish years, you've probably come out ahead for it.