Sure, cost does affect the market value. All I'm saying is that the value of a product comes from the fact that it satisfies one's needs. The production of it does have a cost which is added in the price, but that's true until there's one who's willing to buy it. If nobody wants gold, no matter how expensive it is to mine it, the valuation won't be greater or equal with the cost.

Take oil barrels as an example. In 20th of April 2020, crude oil prices went negative. The cost was much greater than the market valuation, because the demand suddenly dropped.