A player doing occupations can gain certain rewards from them. The most important rewards are special items that massively increase your regeneration for a short time but can only be used outside of combat. However, doing occupations also earns you small amounts of dapper, and can give you items that help with the occupations themselves as well as a special teleport pact.
You will earn dapper whenever you complete a task from the component gathering mission. How much dapper you earn is the same for every occupation and depends on the grade you are in the occupation: At higher grades, you automatically get more difficult component gathering missions, which reward you with more dapper.
The dapper is not the primary reason for doing component gathering missions; the primary reason is getting the components you need for the occupation. The dapper is more of a little extra bonus.