Source: https://www.cbc.ca/news/business/ticketmaster-resellers-las-...
Scalping aside, TicketMaster is taking massive fees each time the same ticket is sold. For example, I went to an event last year and the fee was $50 on each ticket, and these were reseller tickets so TicketMaster had already taken a fee on each of those tickets at least once already (perhaps more than once).
TicketMaster also owns many venues or has exclusive deals with most large venues that prevent those venues from using any other ticket selling platform. The DOJ is currently investigating this monopoly. TicketMaster alleges it is not a monopoly since there are many smaller venues that they are not involved with.