However you can as a pure speculator, just get in and out, sell long and short as you please.
Right now, prices are falling, so buyers are on the sidelines waiting for tomorrows lower price. So, there are not too many customers.
By and large the producers of the commodities need to sell, and are really getting hammered. Arab, Moscow, Iran, Venezuela in the oil markets must beginning to really get desperate. One of these clowns would love for the other oil producers to go off production.
Follow that thought to its logical conclusion and you will realize why the russkies have been goading Iran into making a nuke. If we take out Iran = less competition for russkie oil. Iran takes out a chunk of Arab Gulf production = even better for them (since we'll open up the large can of whoop-a$$ after that).
This commodity and derivative game is still opaque to me. If I have a contract to have a commodity delivered to me in the future at a certain price, how is that capitalism rather than planned economy? A truly laissez faire economy would outlaw such nailing down of future prices. Why wouldn’t the market function in a way that more equates to economic reality if you paid for what is available now for a price that is being asked now? Then too you have the derivative markets which trade the contracts rather than the actual commodities. This is an M&M Enterprises (from the book “Catch 22”)insanity based on repackaging rather than wealth production and distribution.
Economies are left to the vagaries of drought, political turmoil or economic sabotage/monopoly manipulation.