| Equities - Crude oil - I don't get it

Why should this be a commodity that is traded? Should be regulated. So when price of oil was 120+ it was the equity traders pushing the price up? I don't think the demand of oil has changed, in fact if anything the demand of oil usage is still increasing specially for christmas time. Offshore drilling, was that ever the answer.

OPEC has been saying that they were producing enough oil for the world market.

So what's wrong with the scene here?