Great. So you think that a speculator forces the price up when they buy a contract. Then, as settlement date approaches, they sell the contract, but not to someone who might take delivery (that would reduce the possible buyers).
This "forced sale" to a limited set of possible buyers then has no impact on the price. Interesting idea about economics you've come up with.
It works like this:
I have $20, you have $20.
I use oil to make things, you do not.
I go to the seller (who only has one barrel for next month) and offer $5 for next month’s barrel.
You wager that, because I need the oil, you could bid $6 for the barrel and then make $8 off a quick reverse sale back to me.
So, because you’re there, I now have to bid $7. To which you bid $8. And so on, and so on.
Eventually, the price for the barrel *WILL* be $20. But only because you’ve finally realized that you won’t be able to sell me the oil at a profit if you’ve bought it at $20, because I only have $20.
But anything up to $19 is fair game.
Had you not done so, the price of the barrel would be $5, as I’d have been the only bidder.
Eliminate the speculator and you remove a significant portion of buyers in the world oil market. Reducing the number of buyers reduces prices.