If an Iphone doubles or halves in price you would expect demand to react accordingly. Oil has quite inelastic supply and demand. The decade long lead time from greenfield find to bowser means that oil supply, and demand, seems impervious to short term price fluctuations. If you look over the oil suppliers over the last two decades you will see a relatively smooth non reactive output rate - apparently completely uncorrelated to the movement of oil from near $10 to $150 a barrel.
Back in the 70s the OPEC cartel had an oligopolistic control over supplies and could influence price accordingly. Their share is some amount below 40% today. We have seen prices fluctuate from $15-$150 over the last decade - is this the product of some unforeseen demand or unexpected shortfall in supply? Or is simply a bubble waiting to burst? Like the stockmarket, the price of any commodity today should reflect all current conditions and any future expected conditions. So what were people thinking a year ago when they were happy to sell oil at $70? Either they were unaware of future supply/demand numbers or since then speculation has taken over. Using Occam's razor (the simplest solution is usually the correct one) I would suggest it is simply speculation!