In the fourth movie of Harry Potter, when the Death Eaters were at the Quidditch World Cup, why did they have torches? I don't get why they had torches if they had wands that could do the same thing.
Because the films are nonsense.
In this scene in the films, the Death Eaters were deliberately made to look like the Ku Klux Klan:
There is nothing in the book about them wearing pointy hats or carrying big flaming sticks. These elements of the Death Eater parade were added to the film so that viewers could more easily and visually identify them with real-life evil cults.