Anyway back to the point, I know you are buying the private keys but my curiosity is what financial gain you will have with it? I do not see any realistic business in there.
Some tend to believe that they can trick others (maybe authorities?) with claims they had Bitcoins in the past but they don't have anymore. I have some hunches, but nothing clear (and I don't want to give better ideas to others too). However, very shady things.
(Also there are the forks, you know..)