The reason I ask is because I worked for one of the largest traders of physical commodities in the world, and was involved in that trade.

What you're talking about is called cornering the market, and when it happens, the people go to jail. You're using anecdotal evidence to support your claim about a large swathe of people.

Also, if their buying activities meant to create artificial scarcity was the only factor driving the prices up, why did their selling not have an equal effect pushing the price back down?