How might Gregor benefit from his metamorphosis into an insect?
Gregor's life is characterized by giving to others. He works to support his family, while they do afford him the respect or appreciation he feels he deserves. Thus, in becoming an insect, he has been freed from this repressive lifestyle. No longer can his parents use him until he is empty: he cannot offer anything to them anymore. Even though he suffers under their cruelty and neglect, he has all the freedom he has ever wanted. He roams about his room much of the day, which seems to offer him some pleasure.
This transformation forces his family to take notice of him, but the irony is that he is no longer himself, and they have even less desire to be near him now. He is finally paid the attention that he wanted all along, although not in the way he intended. Beyond that though, Gregor experiences life in much the same way after his transformation. He still commits the ultimate sacrifice by killing himself for his family. After his death, his parents turn to his sister to provide the same support for nothing, just like he did.