I suppose working as a fine art consultant, particularly when it comes to procurement, must be somewhat akin to working in the stock exchange. To some extent, it's all luck, really. I mean, you can have all the knowledge in the world, and still not make the right choice, because of unforeseen circumstances.
Fine art does seem like a somewhat stable investment and I suppose it is if you are getting a piece that's by someone very famous, but once you get down from that level and start investing in contemporary art, there is always the risk that the artist will sink into obscurity, or perhaps flood the market with too many pieces which might even be worse.
Picasso, for example, is everywhere. At one point he was painting two or three works per day, which is why those works are only worth a few thousand each, if that. If a current artist suddenly decided to follow suit, it might depreciate all the pieces that had come before.
That might not seem like much of a risk, but if you pay thousands of dollars for a piece and it goes down to hundreds of dollars instead, that's quite a big loss.