Acharya Prashant explains that dreams are inherently limited by the current expanse of an individual's mind. Just as a five-year-old dreams of becoming an astronaut or a soldier based on their limited exposure, an adult's dreams are similarly restricted by their current knowledge and environment. He argues that fixing one's future to a specific dream is a way of telling oneself that they will not grow any further. When a person commits to a dream, they often become closed to new, superior possibilities that may arise as they mature and learn more about the world.