It is a new currency think that fiat has been around for a long time Bitcoin has been around for a little over 10 years. Bitcoin also has a way of injecting new Bitcoin by mining which causes a little unpredictability in the short term because of the amount that is rewarded each block reward but this will reduce in the future helping stabilize Bitcoin. There are also different types of investors atm some are looking to buy into Bitcoin but sell at the price that they define as their target and that causes instability in the market. This should reduce in the future when more people are using Bitcoin as a currency instead of investing to make a profit in fiat.