"And why would the cartel that's capping gold by selling be bidding for gold anyway? Wouldn't they prefer gold to go down or stay down? So who are these guys who have the clout to collapse the price by yanking their bids?"

They are the dominant players in the market; market makers. They make money by encouraging others to buy more as the price rises than forcing them to sell at lower prices when they withdraw bids. The boyz are selling as it rises, causing the fall and buying back (covering) and profiting from their manipulation.

This is common when any one player or group once they get to be a big % of the market is able to move the markets at will. Do you really think oil is a natural S/D market?