The term expresses an exceptionally good performance by someone

The term is used in such a way that if the person (who the term is being directed to) actually is getting paid for whatever s/he is doing, then merely saying the term (and technically expressing the obvious) actually means to express that that person is going above and beyond the job requirements and should be getting paid a lot (maybe more than s/he is getting paid).

If money is not already involved then it just expresses that the person is doing such a good job that it's like s/he is getting paid and still going above and beyond the requirements.

When you eat dirt for the first time and leave your family to build a shack in the woods