Check out Maslow (pronounced "MASS-lov") Hierarchy of Needs: <a href="https://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs" rel="nofollow">https://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs</a> A lot of thought has been put into how people's priorities change as certain needs are met. Of course studies have progressed form that particular model (see "Criticisms" on that page), I'm just pointing out that this can get very complicated :)