The often repeated reason for Bitcoin's continued appreciation is the increasing difficulty in creating new Bitcoins. This argument doesn't make much sense when you look at who is trading. Most traders are not miners, therefore they don't care how much it costs to mine or how expensive a 6990 is. There are already enough BTCs floating around to keep traders happy.
Actually, volume consistently drops after a difficulty jump. Hence yes the traders are the miners. Now it's possible older miners have no reason to trade, nor even to mine that much, but new miners do in fact trade. And newer still are in college dormrooms and at home paying rent. There's a lot of accusations of hoarding which is skewing ppl's estimations of the market.
Also people so this silly thing of thinking of Bitcoin as a single priced item. It's not. It's short term inflationary, long term deflationary. It has a pricing window. When difficulty doesn't keep up there is a volatility increase. When it does go up, the bottom rises and consolidates, while the top panics. The bots from the weekend were truly ridiculous. But circuit breakers could eaily be written into the bots. Don't trade up or down in high speed movements.