Answer:
Gregor is depicted as the 'perfect' son. He takes his responsibility to heart, takes care of his parents, pay off their debts, takes care of his sister. He bears humiliation all in the name of his family, works as hard as he could just to support his family and be their financial backbone.
It is quite disheartening that Gregor was just seen as a means to an end. In the process of catering for all, he lost his own identity. He became what society wanted him to be, the filial son, the dutiful employee, the perfect brother. Gregor took care of everyone but himself.
Eventually, Gregor discovered the harsh reality of life, he was only ever useful when he has something to give, the moment the power to 'give' is gone, he becomes useless, a pest that must be gotten rid of.