The cave isn’t a place, it’s a mindset or belief. The prisoner who went “outside” disengaged from an established belief system and saw reality from a different, richer, perspective. The prisoners still chained would not accept another belief system, or tolerate a challenge to their views. This is how Plato thought of philosophers. They were able to look outside, but were often persecuted for their claims, or killed for them. Like Socrates, Plato’s teacher, and many others throughout history.