In the sutras, the Buddha often taught us that the giving of wealth will bring wealth. Where do wealthy people get their money? They practiced the giving of wealth in previous lifetimes. Therefore, in this life, no matter what they do, money keeps coming to them.
One should not be stingy. Do not be afraid of being defrauded. Do not think that there are a lot of bad people in this world, who always try to take advantage of you. If they defraud you, they will have to pay you back in the future.
The law of cause and effect, what we often refer to as karma, spans many lifetimes. When someone takes advantage of you financially, you are leaving the money taken for future lifetimes when it will be paid back. Do not dwell on this matter. Do not hesitate to do good deeds because of these obstacles. Just as we appreciate material things coming to us now, we will likewise appreciate them in the future, whether that future is close or distant.
~ Based on Ven. Master Chin Kung's 2003 lecture series on the Amitabha Sutra