a very important lesson

A very important lesson can be learned from the shamash, which stands as a servant above all the other candles and does not count in the number of candles. The shamash coaxes all the candles to life and then stands watch over them, ensuring that if one falters, it receives a fresh boost of light. It imparts light to others but does not achieve the status of a Chanukah light on its own. Yet despite this—indeed, because of it—the shamash towers above all the other lights of the menorah. There is no greater virtue than to forgo one's own luminous potential in order to ignite a flame in others.

Source: Vedibarta Bam on Chanukah