A Sense of Contribution - The Source of Fulfillment

Say, a server in a hotel, if only he senses his service at the tables as a contribution to the society at large, notwithstanding his modest earnings, still the quality of his fulfillment could be immeasurable. Thus, expanding on Peter Drucker's 'a first-rate truck driver is better than a tenth-rate executive' we can say that the former could feel fulfilled on account of his sense of contribution, which would be beyond the grasp of the latter despite his material overreach.
So, that is how the sense of contribution is the source of fulfillment in life that mere contentment cannot bring about.