I agree that most of the time with entrenched players it looks like there are no outs. But let's try to look at your example of ticketmaster. Your options depend on how much you are invested in concert-going as entertainment. If not much - stopping altogether might be preferable to further feeding the beast. If a lot - you can explore your local musical scene of amateur bands. The ones that play in bars and other venues that probably don't even sell tickets, or at least do it without relying on ticketmaster. Sure, you'll lose access to stadium-kind of experience, but there will be no change without at least some sacrifices.

I've never been to a stadium gig. I've been to concert-hall shows, with letter/number seating, and no grooving in the aisles; the ticketing experience was horrible. The shows were good, in a way; but I've always much preferred pub gigs and student-union gigs, where you just pay cash at the door.

I live in a major city and even the small and mid-sized venues use ticketmaster… I go to very small shows (basement shows, very small bars) which does sometimes avoid it, but if the band you like is even remotely successful you’re back in ticketmaster’s realm