A Wizard that grew up poor and resentful of the jewellery of the rich people around him decides he'll end the allure of gold and silver for good. For this purpose, he immediately produces a billion tonnes each of silver and gold, and sets around to selling all of it that he can find. In cases where metallurgy cartels or government agencies try to stop him, he just forges coins and ingots himself and leaves them in the streets.
He spends five whole years distributing the gold and silver across the continent, producing a billion tonnes more of each every year. All attempts to stop him with force fail because he's powerful enough that national armies cannot fight him. He does not actually hurt anyone, but neither can anyone hurt or stop him.
His methods of distribution range from leaving the ingots and coins scattered in busy streets to just selling them to major companies.
The world basically our own, except there's this Wizard distributing as much gold and silver as he can, when he can, and wherever he can.
Will his efforts to crash the global market in these precious metals succeed? And if it succeeds, what are the long term effects this will cause to the world economy? What will replace the noble metals as currencies and status symbols?