As a veterinarian and dog lover, I think taking a dog to any festival is a horrible idea! Will you be with it all the time? No- you'll be checking out music. Maybe partying.
Will the dog be scared? Of course!
Could it suffer from hyperthermia? Yes.
Could it get stolen? Yes.
Could it get in a fight? Yes- if there are other aggressive dogs there.
Could anything else go wrong? Yes.
Will you be equipped to be its best advocate and guardian 24 -7? Unlikely.
Be responsible and get a dogsitter.