You guys don't understand - the whole premise in incorrect. It's wrong. Dead wrong. Proved wrong by logic. Palm hitting forehead wrong.
Goldman Sachs may do really bad things, but buying oil futures (or their own stock, or crappy mortgages, etc.) isn't one of them.
Making a voluntary transaction for oil futures is not a crime! It sends more information to the market!
If they are buying oil when the price is too high, then they will lose money when the price reverts to equilibrium.
The word "speculator" has such a negative connotation. Anyone buying and selling stocks/bonds/futures/whatever is speculating. This is very important information that is communicated to the market.
Speculation does not interfere with supply and demand. Speculation is part the process by which supply and demand adjust.
http://mises.org/story/2381
http://blog.mises.org/archives/008327.asp
As for the Great Depression, Taibbi says: "The trading corporation then relentlessly bought shares in itself, bidding the price up further and further. " Yeah, it's called stock buybacks. It's a voluntary transaction. They are forcing no one to do anything.
And in the recent housing crash: "GOLDMAN SCAMMED HOUSING INVESTORS BY BETTING AGAINST ITS OWN CRAPPY MORTGAGES." Yeah, so? It has a bunch of traders. They do whatever they want. They buy and sell in the market with other people that want to buy and sell.