I think that the want of things is a matter of nurture over nature. However, I believe the tendency for one to be more inclined to want more than others. Example, a child whose parents deny or limit in the extreme basic needs may cause a child to grow up with a greater desire to WANT more in order to compensate for what they lacked as a child. Conversely, a child may grow up the feelings of entitlement and believe that the world owes them more.In both cases I blame the parents for not moderating their child’s psychology. Culture is also a motivating force. Growing up around people who always strive for more than they need will also cause this sense of need. I would blame religion but it is really a lack of ethics and that may or may not be a failing with religion but more of a sense of a lack of identity and self esteem of the greedy person.