What novels, films or quotes reinforce the idea that 'People often need to grasp onto delusions in order to manage with reality'?

Ender's Game by Orson Scott Card addresses the theme of illusion
versus reality perfectly.  In the novel, the military train Ender, a young gifted boy, using all
sorts of strategy games and battle simulations;  the government is desperate to cultivate a
master-mind commander who can take control of their space fleet to...