Now you are starting to catch on. The only currencies that don't fluctuate are the ones in countries run by thugs. However there always is a black market rate which does fluctuate. The ability of a currency to fluctuate is proportional to the thuggishness of its creators. Since bitcoin is completely distributed there can be no thugs. Therefore its exchange rates are always free to fluctuate.
Nope. I've always understood it. You still don't seem to see that you are contradicting yourself though. You agree that the values of Bitcoin and various other currencies fluctuate with the market. Yet you also say they have defined exchange rates. Those are completely opposite positions. Allow me suggest that the position you cannot demonstrate might be the one that's wrong.