According to Chapter 50, why is a Guru so important, and what are the main things that prevent someone from gaining true knowledge?

Chapter 50 explains that a Guru is indispensable because ignorance arises from doubt (vikalpa), and this doubt cannot be removed without a Guru's intervention. The text warns that even a wise person can become prideful and their knowledge corrupted if doubt enters their mind, comparing it to how a drop of fermented liquid can spoil a whole pot of milk. The chapter also identifies key obstacles to attaining true knowledge. These include a mind fixed on wealth and luxury, dissatisfaction in sense enjoyment, and being constantly preoccupied with thoughts of one's wife and sons. A person deluded by these attachments, even if considered 'wise,' is described as having their knowledge covered by ignorance.