Silly people.
You buy it for $10k in 2005 and sell it in 2014 for $15k. You lose $3k in consignment fees, leaving a small profit of $2k. You are right about investment potential, but you aren't counting the fact that you can't frame a mutual fund and hang it on your wall. Whomever is now selling received 20 years of pleasure from owning and displaying this piece.