Why does Chapter 8 argue that a life focused on nourishing the body and pleasure is 'useless'?

Chapter 8 presents a strong argument that a life centered solely on nourishing the body and seeking sexual pleasure is a useless endeavor for a human. The text reasons that if these activities are the only means and ends of life, then humans are no different from animals like dogs and pigs, who also fill their bellies and reproduce. As explained in Chapter 8, the human form is wasted if it is only used for the four basic activities of eating, sleeping, fear, and mating. The true duty and unique potential of a human birth, according to the chapter, is the attainment of the Supreme Self (Paramatman), making a purely materialistic existence a missed opportunity.