If the world portrayed in Fahrenheit 451 is supposed to be full of people who experience nothing but happiness, what is one reason that would explain why there are multiple examples of violence in the book?
Bradbury explains in the book that violence is part of human nature, and will still exist in the future no matter how happy people are.
Although there is much violence in the book, all examples of violent behavior are unintentionally committed. Because the people in Montag's world don't think, they end up mindlessly and accidentally being violent.
The characters who commit acts of violence in the story are all characters who secretly read books. This explains why books have been banned; reading violent stories cause people to act in violent ways.
Bradbury, by creating a populace that is both happy, and yet war-ridden, is trying to convey that happiness does not necessarily bring about peace.
The multiple instances of excessive violence in the futuristic world of Fahrenheit 451 reveal the problematic dark side to this culture such destruction provides evidence that the perception that the idea that this society is uniformly happy is merely a facade.