I can see why people do it. Personally its not something I'd do, though.
For example. About a year ago the team i support - West Brom (no accounting for taste, i know) Got to Wembley twice.
West Brom were only making the tickets available to season ticket holders/share holders etc. So i got a bunch of extra tickets and just gave them to my friends at sale value. Didn't even charge them the postage costs.
chuzzlemonkey up for best friend of the year??