I already answered what drives the market, it's rather simple but in accepting my explanation you also have to accept there is a disguised pyramid in effect in the form of mining hardware prices and ever increasing difficulty. When miners can't ROI they hoard their coins, it created artificial scarcity and all new buyers gobble up the coins until they are at a price that makes it viable for miners to see a ROI on their mined Bitcoins.
Maybe true for hobbyist miners. But the big miners have running expenses they need to cover. So quite the contrary is actually true. If the provability get's lower they are required to sell a larger and larger percentage of their income in order to cover their expenses.