Ticket revenue is just one source for the artist who is betting they make more from the lifetime value of a fan buying their brand (merch and historically listening to their music, but I don’t know if streaming changed those numbers). It’s like a giant advertisement for their brand - It can even be a loss leader after all the crew is paid.

A key part of that concert experience is other people’s excitement too. For one extreme, a Grateful Dead show was basically a mini festival with one act. The crowd before, after and during is why many went.

So, a Dead show that sells just a few hundred many-many-thousand-dollar tickets might sit on a maximum supply / demand curve for the venue or scalpers just looking at ticket revenue, but could destroy much of the value of the event for the band and it’s everyday fans who want the event experience and want it for as many people as possible.