The Lollapalooza Music Festival in Chicago annually is youth oriented. They can be wild and even lawless as you can see in the following photographs. So there is risk. You will be on the front lines of the gospel battle for souls there and anything can happen, particularly if you are not wise as a serpent and harmless as a dove.
Remember, they are not aware they are doing anything wrong. The festival is legal. Neither is it free and you were not part of the deal; so be as polite and gentle as you possibly can realizing they came to have fun, so they might want to have fun with your solemn self.
And the Chicago police. Well, they don't have the best reputation in the nation. They will come to guard the festival more than your rights. So be ready.
You will be preaching and witnessing at a big city party which requires skill and knowledge of what to expect. This
crowd will come rain or shine. They do not intend to miss the fun.