If the friends know everything, then they should also know that they are not the ones suffering and those who are wicked may not suffer in the world. Creation, your senses, and wisdom which comes with age should reveal truth, but the friends only rely on wisdom. The friends should know that Job suffers unjustly. Jesus himself suffered unjustly and knows when we, forgiven in him, suffer as those who are not guilty of sin. When we suffer free from sin, we suffer as Christ suffered and have hope to be delivered from suffering as Christ enjoys the heavenly places.