To be an effective trader, basically what you do is step in to a transaction between two people and shove them far enough apart that they can't communicate. Then you go to the seller, tell them that you and your buddies are their only market and you will pay them $XYZ for everything they have. A real low-ball figure. Do your best to put them in the fucking poor house.
You then take whatever you bought to the person who was already interested in buying it, and tell them you and your buddies are the only source for whatever it is you bought, and if they want any of it they'll have to pay you $XXYYZZ. An absurdly overvalued figure. Do your best to put them in the fucking poor house.
What's going on is that traders at no point are about facilitating exchanges between two parties. Every step of the way, their goal is to screw everybody who's still holding a single red cent so hard that their fillings fall out, and then collect those fillings -- gold, too, is an investment.