that is because rather than look up the easy to find stats on Chinese demand, you would prefer to go with the conspiracy theory. The reality is that I did and/or used to work for a large "oil company" and I can tell you as a fact that we sold our products on the open market in a very competitive environement. Yes, OPEC can tinker with stuff here and there, but to call it a monopoly is just plain wrong.
I will check the stats. I admit I've never really looked them up. But my gut tells me that the demand from China alone could not possibly account for the difference we're seeing at the pump.