As others have stated, conclusions about character cannot be drawn based upon one's fiscal resources. Great wealth can be both accumulated and lost through amoral decisions. Saying that one's poverty is the result of poor decisions is, to me, akin to holding that the wealthy individual likely accumulated his resources dishonestly or through inheritance, or are stingy.
Personally, I rather relate these stereotypes to those associated with overweight individuals. Like most stereotypes, there is at least a grain of truth present. If one consistently makes extremely poor diet decisions and does not exercise, weight gain will result. However, this certainly does not mean all fat people are lazy or gluttons. Similarly, gambling, alcoholism, and similar will, under the vast majority of circumstances, lead or contribute to poverty. This, however, does not make it accurate to associate all cases of poverty with such decisions.