It's wrong to say things to make others feel hopeless.
Billy is talking with a friend who keeps on complaining about his life.
Billy is irritated by his friend and wants him to stop bothering him with his whining.
Billy convinces his friend to try a new way of coping, which involves thinking only about the positive things.
Billy tells his friend there is no point in them talking about this anymore because his friend's situation is never going to improve.
Billy's friend starts seeing that things in his life are actually not that bad and feels better.
Billy's friend feels terrible and goes back home thoroughly depressed.