We trade a view of true reality for a view of fitness for our survival. There was a TED talk by someone who talked about how they ran a simulation with three types of organisms: blind, view of true reality, and view of fitness for survival in that moment. View of fitness absolutely dominated. Your brain doesn't care about being right. It cares about keeping you alive, and if that means using cheap and dirty shortcuts, guess what, I hope you like optical illusions.