Scalpers exist because legal concert tickets do not respond to shifting demand. This makes scalpers an essential part of the system.
Concert tickets do not respond properly to market demand because:
1) Performers are often concerned about seeming too greedy or they want tickets set at a price their fans can afford;
2) If demand is underwhelming promoters don't like to cut prices because of the optics (scalpers, OTOH, have no problems doing this).
There is no easy way to fix those issues so scalpers are inevitable.
There is nothing immoral about selling a ticket to a willing buyer at a high price. That is the essence of our free market.
It is not as if concert tickets are essential.
The only problematic issue is if scalpers prevent people from buying tickets because they are able to game the system.
Ticketmaster needs to prevent that.