alt Hacker News> Anyone with a legitimate reason (giving to a friend etc) can work it out even on the day of the event.
I've seen it happen multiple times people couldn't find someone to take the ticket off of them, even for free.
Sure, for an ultra mainstream act the likes of Rammstein? A FC Bayern soccer game? You'll always find some people outside the venue willing to pay in cash for tickets.
But anything with a small fanbase? Whoops.
If you were honestly just looking to sell your ticket at a price that recovers your costs, I think you'd have an easier time pre-planning a trade.
But there's definitely a balance to be found between the popularity of an event and how soon you allow trades.