(Even if the control isn't formal, owning a large percentage of a finite "thing" still counts as control, if the "thing" is the unit of exchange for people's work, property, etc. A BTC economy would depend on what the large holders decide to do with their portion).
With Bitcoin, the community that controls the money supply is not at all democratic; it is the early adopters with large holdings that carry all the weight.
From the perspective of a non-early adopter, the Bitcoin world would be even worse then the central bank and government world. Banks can be regulated and governments can be thrown out. Bitcoin would create a tyranny of "hodlers" protected by intractable mathematics.