Look at it from both directions. When they sell their existing stocks, they have to replace it with higher $ stock. But when prices drop they can't sell their more expensive stock at the higher price they paid because someone else will be selling the cheaper stuff right away. Commodity pricing is less a function of the makers than the commodity market. You can buy & sell oil or beans you don't have. It's called speculating! Risky! Big bucks can be made or lost in a very short time. You can do it, anyone can. 10 to 1 leverage is common. Buy 1000 bu. of beans for $10/bu. but only have to pay $1000 + some fees with a promise to pay off the rest by a certain time. If the price goes up by $1, you sell and make a $1000 profit on a $1000 investment, less a little in fees. But if the price goes down by $1, They sell you out and you've lost your total investment. Of course there is more to it than this but you get the idea.
The game gets even more interesting when there is a big run up in prices. People jump in to make the big bucks. More contracts are sold than commodities to fill them. If the price dips a little there will be mass selling to keep from losing either their paper gains or their total investment. It can turn into a snowball. If there are more sellers than buyers at a given price the price will drop until it evens out. That puts more pressure on those that got in at a cheaper price. They then have to sell to keep from losing their a$$.
Limits were put in place after the 1920s market crash. But the game can still be played. Not my cup of tea but you may want to see if you can make the big bucks. There are some catches not covered here. Inflation will raise prices but not value. The government will collect taxes on any of you're $ gains even though you haven't gained any true value. The government will use those cheap $s to pay back the more valuable $s they had "barrowed." Inflation is a barrower's friend!
