You should also consider that with some ticket bought online or from vendors outside the venue, drink or drinks are not included. It's a messy thing when you start calculating what's profitable and what's not. Also you get the discount coupons and bracelets for some events so that's also a thing to consider. For example We Love is about 55 euros and discount coupon you get 20 euros off and a one free drink so you save some money, of course, if there's 10 people, can you get 10 discount tickets. But if you get them, you will make some summer worker really happy.