I noticed that the price of Bitcoin change much like all altcoins.
But the price of other traditional currencies like the euro, for example, are stable and do not change much.
It is the government that control their prices?
Other currencies are not like bitcoin, it is not something that is not controlled by the overall market there is no constant demand on it the Euro and Usd are being used on everything by producers and consumers so it is always moving so its price never goes up but as for the bitcoin it is controlled by the community and if they want to use it or not if bitcoin was used so often then its price won't change a lot.
You right, fiat has been used for trade long time ago, so the price is have more stable high-low, besides that it's controlled by government, which means the price also have intervened from government. But all currency basically move based on supply-demand.
Bitcoin have less supply than fiat, means although it's used more often than nowadays, there's possibility the price also change a lot.