Acharya Prashant explains that the concepts of good and bad are entirely relative to an individual's internal state and context. Using the analogy of blood pressure medication, he notes that what is life-saving for one person can be poisonous for another. Therefore, no one else can truly determine what is good or bad for an individual because they do not know that person's internal condition. He emphasizes that focusing on others' opinions indicates a lack of self-awareness and suggests that one's primary focus should be on internal discovery rather than seeking external validation or advice.