Why does Locke turn bad in lost?

In "Lost," john Locke turns bad primarily due to his deep-seated insecurities and feelings of betrayal. His initial belief in the island's mystical properties and his role as a leader becomes corrupted when he faces manipulation and rejection from others, particularly Ben Linus. This leads him to adopt a more ruthless approach, culminating in his eventual betrayal of his friends as he seeks power and validation on the island. Ultimately, Locke's journey reflects a tragic descent driven by a longing for acceptance and purpose.