Mary Jane: courageous or naive?

When Mary Jane is constantly warned by the good doctor about the fake Wilks brothers, she decides to go ahead and give them her entire inheritance to invest as they see fit. She seems to see this as a courageous and heroic act, showing the entire town that she will do as she sees fit and that she has faith in her "family", regardless of the facts presented against them. However, rather than being courageous, I think Mary Jane is being naive. She seems to think that they could not have tricked her, regardless of the evidence that the doctor presents against them, and the fact that they seem to have no real proof of being her family. She puts her entire inheritance, and her sisters, in the hands of relative strangers, family or not. This action is just downright foolish. I think that the smarter action would have been to defend her "uncles" and to continue to care for them and house them, but to have kept the money to herself. She got extremely lucky that Huck decided to steal the money back for them, otherwise the sisters would be completely poor and all alone, thanks to Mary Jane's decision. So, I think that Mary Jane wasn't being courageous, but she was being foolish.