besides, the market is not really big
Currency is supposed to move based on perceived and actual value. Compared to fiat currencies Bitcoin is the LEAST manipulated. People can play around in the market but almost no one can really manipulate the price. In the fact the main people that have been able to affect the price for a temp time have been the government who dumped artificially not worrying about the price. But this is only temp, no one can actually hold the price up or down for any length of time.
The dollar is 100% manipulated cause the government have the ability to alter the supply.
Yes but the difference is that with the Dollar you can plan your shopping for the following week to the nearest cent, with Bitcoin by the time you complete your 10 min walk to the corner shop, your $100 worth of Bitcoin could be down to $20. The price of BTC may seem stable now but everyone knows that could change in the blink of an eye. Also, Bitcoin can very easily be manipulated, a lot more easily than fiat and with lot more damaging effects. 1% of Bitcoiners control 99% of all Bitcoin in existence. For instance, Satoshi could very easily move the price of BTC to his whim with his estimated stash of 1,000,000 BTC.