That might be the most literal interpretation of "selling pickaxes during a gold rush" I've ever seen. The analogy is absolutely fine.
Like it or not, it's a phrase that dates back to Mark Twain that has far more baggage than some strict analogy made up on the spot. For instance Chris Dixon here[1] suggests that Heroku and Akamai sell pickaxes, not dynamite as a service or scalable ore transport systems.
All I'm doing is defending the GP's use of the phrase, which was absolutely valid. Perhaps you'd have used a different analogy, but it doesn't invalidate his. No quantity of curt denials you care to throw my direction will change this.
[1] http://cdixon.org/2011/02/05/selling-pickaxes-during-a-gold-...
Creating mining hardware is actually more speculative than an exchange, because you're picking winners and losers based on what your hardware can accelerate.
Selling pickaxes to miners has been used to describe platforms like CDNs or game engines like Unity. The fact that there is something called a miner in this context is a red herring.
A metaphorical one, I mean.
I don't think they are speculating though, they are simply doing what they do and have always done. Provide a means of exchange from national currency to digital assets. It is up to the people who build around these protocols to create more ways of utilizing these digital assets through services.
It's hard to say what's going on in this market but I don't think it's a bust. A lot of money went in really fast and then huge sell offs from Mt Gox recovered bitcoins. Bitcoin is still somewhat interconnected in price with most altcoins because of pairings, and any major selloffs seem to drag the whole market down. I think it will mature in time and more people will actually utilize cryptocurrency and not just buy it for speculative reasons. Value will be established over the next few years as practical use grows.