Along with all of the other issues already mentioned, like systematic biases and such, there is another simple possibility that is definitely a factor: impulse

Along with all of the other issues already mentioned, like systematic biases and such, there is another simple possibility that is definitely a factor: impulse control. If you have good control over impulses, you like are less likely to give in to the impulses to spend money unnecessarily, and this more likely to be financially responsible and thus less likely to be poor. I'm certain plenty of spontaneous petty crime comes down to poor impulse control in the moment.