Great question, I wouldn't go oil just in case green gets momentum. Actually, I wouldn't go any natural resouce just in case science figures out how to replicate any molecule, rendering them all worthless.
So yea, I think an interest in human endeavors is the way to go, whether currencies or shares of Microsoft, best as you can spread it around. If I were truly limited to one investment, I think I'd try to back end into one of the time-honored vices, prostitution or gambling, maybe even Real Estate on the Strip, but every decision here is fraught with danger. |