Why the price of bitcoin is changing quite fast....Why so?
Supply and demand. Simple economics.
Right now a lot of new people are being introduced into bitcoin and this is the reason why the price has risen so much in the past few months, pretty much exponentially. Bitcoin is quite volatile because it is completely unregulated, no government will bail out bitcoin etc.
This volatility in my opinion just shows that bitcoin is independent to fiat, and can generate a lot of profits for you if you speculate right. For example right now BTC is down a bit, buying right now could easily prove to be a $500 profit per btc bought.