Why does my 13 yr old cousin want to work and my 29 yr old brother with 8 kids doesn't?
She changed the question while I was posting, my answer so its different now.
I think the reason is that kids want to make money because there is something they really really want, probley a motivation. It sounds like your brother is simply being lazy and feels there is no "reason" for him to get a job.
People are different, you're asking about different personality types, it's really less about how old you are and more about how mature and responsible you are (and unfortunately age is not a guarantee of either)
thank you both for answering