I seriously doubt if that will work. Because what Sara is describing, sounds a lot like Kleptomania (which is basically an addiction to stealing). I too have come across such people a few times in my life, so I think I can recognize the signs.
You of course are thinking logically, which is very good. As logic dictates that if she could get a job and earn her own money, and then buy things from it - Then she will learn the true value of money (and so probably become more mature too).
But here’s the problem, Kleptomania is a mental problem. So dealing with any form of madness with logic, hardly ever gets you any results… See link below to learn more.