People learn behavior by observing and duplicating the behavior of others. This starts in childhood - and continues thru life. This can lead to conflict. If one person wants something, another person sees that desire and wants the same thing. Now there are two people in competition for the same thing. This can happen to large groups as well.
Eg. People want wealth(beyond their needs) because other people wants it too. This creates a feedback loop that leads to wealth accumulation rather than better distribution.
This might only apply to things above basic Human Needs.
Idea based on theory by Rene Girard