In fact, what people see, depends very much on what they the are supposed to see. Instead of saying “Seeing is believing.” We should say “We see what we believe.” And this results in huge errors in perception and judgement.
The world people believe in, is often far different from the way it really is. And they strongly resist changing themselves, and what they believe. They would rather die, than change – and many times, do go to their graves, firmly believing they are in possession of the truth.
More frequently, however, they manage to live with more subtle alterations of the way things are (or Reality). This is not good for their health (especially their mental health) but this damage is something they can live with – and may enjoy very much. And may attract other people to them.
People can enjoy some kinds of craziness. And even find it entertaining.