I too find the trinkets pretty pointless, but I think their presence in our current economy probably goes towards subsidizing the ticket price. The sponsor pays the venue, say, $25 per attendee to give away the swag that costed somebody $2.50, in theory the net benefit is passed off to the attendee in some way if they don't mind being sold to.
In a few cases, like my treasured, octocat figurine I posted in this thread, it seems like a win-win-win where the trinket isn't pointless. But yeah, this kind of appreciated value is usually lost and the whole effort is wasteful capitalism.
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