the reason is why so slowly, because industrial btc owners (knc, terra, bitmine, bfl, etc..) doesn't helping. so there is the difference between mortal (as we are simple users) people, when it goes up slowly. bei immortals like knc, terra, bfl, etc.. it goes in 5 days 1000% up. the advantage when the mortals are trading is the stability of the currency it wont popup 20% up and down.. you can take the grow rate right now (8.Dec.2013-10.Dec.2013) and calculate how much BTC going to cost in 2 years with circa 10%-20% accuracy.