There’s no set size. It’s just that one rich guy can’t command one hedge fund to do the buying for him because it would look highly suspicious, if not illegal. Some of my doctor friends in hedge funds would likely pull out because the fund isn’t doing what they want it to do (they don’t like the idea of one person controlling what is supposed to be a diversified fund, or doing what the fund manager is supposed to be doing). The last thing a hedge fund wants is an investigation from the CFTC. So, the rich person has to diversify his purchases. This becomes logistically difficult, something like trying to buy all the lottery tickets for all possible combinations at one convenience store. On top of that, who is coordinating all these purchases? Where is the money coming from? This becomes all very easy to trace. So the market manipulator would have to employ a team of people to do this, thus cutting into his profits.
For every long position, generally, there is a short. Whoever is in the imbalance is left holding the bag. In this case, longs outweigh the shorts, and last I heard, that was 170 contracts. That’s 170 deliveries of oil that someone has to take. If that person is not going to take the oil, he has to put it somewhere. The oil supplier doesn’t know who is going to buy his future contract, but I suppose, he could choose not to sell any (assuming he is able to get into the futures market in the first place, and that is being in the long position without a shorter) but that’s an awful lot of risk, which I’ll address below.
However, you must understand that consumers don’t fight for lower oil costs or lower speculation at this point in the market. Consumers need the oil now. Consumer compete on the spot price of oil now, which is not influenced by the futures market.
I suppose it is possible, but the logistics of coordinating such events is massively improbable. Assuming that there is a consortium of players, and assuming they can all agree to divide the spoils somehow, one person can undercut them all and expose the rest of the consortium’s positions. A more simple way of understanding that is how member of OPEC routinely break their agreements and sell oil anyway.
For your second question, if the future contract holder can’t zero out his position (find a shorter), then at the expiration of the contract, he must take delivery or sell (he’ll often just sell at a lower price). The oil supplier won’t know this (plus he would have to be able to sell to himself on the futures market, also a logistically hard thing to do) in the future. How will he know how to ramp up production? Hopefully, I’ve demonstrated how much risk there is in all this. If a new supply of oil is found and the price drops, the long holder will be very exposed and crushed from the forthcoming margin call.