Well if you are a venue that puts on big shows like this, you kinda like Ticketmaster. They pay you a commission to be able to sell your tickets to the public, and they can afford that because they charge service fees at the expense of the consumer. Now, if you are the venue, you can obviously sell your own tickets on your own website, but Ticketmaster is simply a third-man service that cuts out that effort for you. So you get paid by Ticketmaster - not as much as you'd make if you charged your own (smaller) service fees, obviously, but you don't have to worry about distributing your tickets. It's just outsourcing work for convenience.