GDX was depressed just because investor did not believe that gold price can go so high and the gold price can hold for long. So they just manipulated GDX for profit. GLD gold holding position always under 1300 tonnes even gold price had been skyrocket and Western investors have not increased any gold holding. Most gold was bought by Asian countries. These phenomena will be continuers for long. So GDX value will show its value finally. GDX is same level as gold under $1000, I wonder who don't believe that miners can not profit better with $1600 gold than $1000 gold? Why GDX should be so depressed? Gold miners did not benifited from high gold price? Where the logic is?
I've pondered this many times. What you've stated is true and logical. Any person with sound reasoning skills can see this. The problem is PM miners are controlled by HFT, computers with no brain, just a program. There is no reason for miners to go down as the stuff they mine goes up for this length of time. But I believe they will turn greedy to the long side again and sentiment will change. When? The monthly and quarterly stochastics are bottoming now which means there could be a sustained period of higher prices soon.
While I agree with GDX going up in the long term, your opinion about GDX being controlled by HFT is preposterous. It simply looks to be filling the gap from MAY when it slid to $39. Go look at the chart, it gap up and never filled. By under $40.