Acharya Prashant explains that the difference between fear and curiosity when facing the unknown depends on one's fundamental outlook on life. He uses the analogy of two houses: in one, you trust the owner and explore new rooms with curiosity; in the other, you feel like a prisoner and view every new sound or closed door as a threat. Most people live in fear because they have been conditioned since childhood to believe the world is a dangerous place. This deep-seated suspicion makes every unknown situation appear frightening, leading people to build walls and live in a state of constant mental imprisonment.