She is still alive, an accomplishment that puts her in the ninety-ninth percentile, way, way ahead of most of her class.
This notion that Sera has value continues to be drilled into us by the narrator as her thoughts and feelings. The implication is that most hookers are dead by the time they are her age, and she is actually living well, just as well as anyone else who has a normal job with all its accouterments like doctors and a place to live and the ability to buy groceries. She believes this fact means the downsides of her profession - the times when she is physically abused and the times when she is scorned, are small in comparison.
