The comments about gold mining costs being higher as a price support floor is invalid. First the only reason it's higher is because the higher market price led miners to invest in low margin mines.
Can you give me a source for that?
It doesn't sound very logical to me: If the price of gold has just steeply risen to $1000, I would have to be a complete moron to open a mine that only renders profit above $900 (to give an extreme example, you get the point). It takes a relatively long time and much effort to get a mine running, so when one considers opening a mine, they can't calculate like that (with the gold price in steady motion, manipulation, etc..).
Market prices are just bets by market participants with production costs being one of many different factors.
True, it's just one of many factors - but a very important one. What comes into play here is that the current price of gold is mostly a product of manipulation (if it wasn't, there would be a lot more weight to that argument of yours).
As I said, there would be many, many other things to mention - but it would take a lot of time to go into them in detail, so I just picked production costs to have a closer look at. Most of those other points make an overwhelming case for gold as well.
EDIT: You make a very interesting point for sure, but I think my main objection is that this kind of thinking is not relevant anymore when the TRUE price of a market would be so much higher without manipulation.
Is price a function of existing production cost or existing production cost a function of price?
It's a bit like asking "Who was there first, the hen or the egg?" You have to look at it on a case-by-case basis, and for me the case is quite clear here, considering where the price gold would be at without all of the manipulation. That's the difference to the BTC market as well.