I think that the primary motivations in seeking higher elements within management levels comes down to extrinsic and intrinsic elements.  One primary motivation in becoming a supervisor is extrinsic.  This might be in the result of more money, greater amounts of compensation, or greater title associated with an individual.  These extrinsic elements can help convey a sense of worth that the individual feels towards their task that are outside of the task itself, helping to solidify the desire to pursue supervisory levels of management.  I feel that there are intrinsic motivations behind why one would wish to pursue a supervisory position.  Perhaps, there is a belief that one could enhance a particular work climate or give something to make the overall function of an endeavor more effective in the role of management in a supervisory capacity.  This could be something in light of mentoring or assisting newer employees in the process of an organization's overall purpose or function.  Another intrinsic reason one could pursue a supervisory activity would be that one feels that a new level of challenge is needed in their particular work capacity.  Perhaps an individual has worked at one level for quite a while, acquiring a certain amount of skill at that position.  Moving into a supervisory level might provide a new sense of challenge and a new focus for an individual's work in a particular organization.