A few examples of “special” events and how these things could go wrong:
Okay, I lied. While these things aren’t necessarily “realistic,” they are all possible! Right?
Most likely, when you host a large event, the venue will require insurance. In the case that no one shows up, or your DJ cancels on you in the nick of time, the deposit costs are covered. In the case that a drunk lady dancing stumbles into a table, knocks over the punch bowl, ruins the carpet, and falls to the ground breaking her arm, the damage and medical expenses are covered. Life happens in funny ways sometimes, but it’s not so amusing when it costs you a lot of money. Insurance covers unexpected occurrences.