Hi projectgait - what an amazing question. I can't resist adding my 2 cents...
The research I've read in this area is that paying someone to quit works "sometimes" for "some people". But actually, not very often. If it worked for most people, I think insurance companies and social health systems would regularly offer people $ to quit. This would save not only on a lot of future healthcare and lost productivity costs, but also a lot of heartache.
This reminds me of a fairly recent study I did on our communities. I thought, at the beginning of the study, that I could predict who would be motivated post and who wouldn’t. We looked at factors like demographics (e.g. a user’s age, gender, occupation, education, etc.) and disease severity (e.g. how long they smoked, how many cigarettes they smoked per day, how many times they quit, etc.). Well…
I was dead wrong. Totally wrong. It turns out you can’t predict who will post (and who won’t). If interested, you can read the study here: https://www.jmir.org/2017/2/e40/
My point is that it’s hard to figure out what motivates people. What motivates someone to post? What motivates someone to quit for good?
My guess is that if $ is super important to your brother, more important than smoking, it can be used as a tool to help motivate him quit. However, I think it turns out that in moments of severe cravings a lot of things take second place to relieving the pain of withdrawal.
I'm also a former tobacco user and although I quit a long time ago the thought of having to go through the process again is a strong enough motivator to stop me from using tobacco again. The thought of using tobacco again actually repulses me, but the thought of going through that again is even stronger.
Note: this should not stop someone who is struggling right now. In fact, even though they may be miserable in their quit, it DOES get better with time. The desire to using tobacco will one day - believe it or not - go away entirely.
In any case, what a great question!