I agree and disagree.
On a micro-scale, a daily basis, I agree - it may even look that the miners follow where the money is.
But on a macro-scale, over a long period of time (1yr) and if you include all the coins? That, I am still not convinced. I still believe that the mining group does increase the overall market cap of all the coins, eventually. The miners provide the product that the speculators need (or will need). Over a 6 months to a year period, the two balances out. But because we are in a period of growth, the miners are putting more money in the system than the buyers of the coins. And that is normal, the coins have to be mined first, like the shovels have to purchased before any ore can be discovered.
It doesn't matter if there is one person mining, 100, 1,000,000, or 10,000,000. The same amount of bitcoins are "supplied;" 25 bitcoins every ten minutes (with the obvious caveat of the rising difficulty bumping that number slightly higher than the block target, etc.). Somebody gets them.
The cost of mining equipment in total doesn't really matter. If there is an increasing amount of miners such that the difficulty continues to rise, it encourages hoarding - that much we already know. This aids
indirectly in scarcity. But the amount of hardware invested into mining equipment does not drive the price of bitcoin up.
EDIT: And the minute the speculators will stop buying at the global price (to include all coins) - the miners will stop buying new equipment and the prices will eventually level off - at last!
The minute that speculators stop buying bitcoin on the exchanges at the current price is the minute bitcoin's price declines. And when bitcoin's price declines, the prospective new buyer's cash doesn't flow into the buy side of the market. Because afterall, nobody wants bitcoin if bitcoin can't prove itself as a competent store of value.
New cash flowing into the exchanges is what will drive bitcoin's trading value up. Not the increasing sum total of the value of mining hardware.