What is the problem in monster inc?

In "Monsters, Inc.," the primary problem arises from the energy crisis in the monster world, which relies on children's screams as a power source. However, the monsters face a dilemma when they discover that laughter produces more energy than fear. The story unfolds as main characters Sulley and Mike attempt to save Boo, a human girl, while navigating the challenges of their industry and confronting their own beliefs about fear and laughter. Ultimately, they seek to change their society's reliance on scare tactics to something more positive.