I think what makes this bitcoin price increase is because of the good news circulating on the internet and the total supply and algorithms for mining blocks are increased, making bitcoin very difficult to obtain and the price becomes very expensive.
The limit in amount of coins is probably one of the most important factors when it comes to the value bitcoin, because if there was not such a limit I know that I will not be holding bitcoin because that will mean that an unlimited amount of coins is going to exist, fortunately for us satoshi understood that in order for something to become valuable it needs to be scarce as well.
Investment cap, positive and negative attitude, trust of the people, demand and supply are the factors that affect the price and cause ups and downs in the market. The market now is suffering from strong correction and the investors should stay and hold their coins for more time. Hope that this situation will end up soon and good days will start in near future.