Polite people do get burned out and tired of serving others, but still keep good grace around them. They can still have those feelings, but they might choose to repress it for a later time. We aren't all nice ans polite to each other, maybe because they don't feel understood, or are saying something that they would rather not say aloud, if you get my drift. I don't think it is because of the sinful nature. Everyone is rash at some point.
This is based on the information given in the query called the Token Economy.
This type of economy focuses on rewarding individuals with tokens (or in this scenario) to accomplish specific tasks or to perform desired the behaviors.
These tokens can then be exchanged for the desired gift or the privilege.