Why there will always be eternal economic unease and conflict?

First,  you must understand that economics is not a science.  Using the classical definition of economics–it is the study of human behavior in its historical setting. In other words–economics is the study of psychology. Once you understand this, the answer to the lead question is simple.  Human wants and desires are unlimited, but the economic means and resources to satisfy these desires are limited at any particular point in time.  This result leads to a state of human agitation and conflict.  The conflict can be expressed on both the personal and societal levels.   You can not eliminate this conflict, but you can reduce it by understanding its nature and human limitations.  After all, mortals are not perfect.