I disagree. While it would do a lot of damage, the advantage of a properly scalable and functioning decentralized cryptocurrency (not implying BTC is the right

I disagree. While it would do a lot of damage, the advantage of a properly scalable and functioning decentralized cryptocurrency (not implying BTC is the right one) is that it cannot be controlled by any central bank, or anyone else. That is the inherent elegance of such a solution. While in the Western world there is little need for a parallel monetary system except for the black market, other countries are not as fortunate and do not trust their central banks with anything (classic example is Venezuela). You could argue Gold is still a good alternative, but owning, transferring gold is problematic unless you actually store it yourself. Any "title" to gold somewhere else can inevitably be seized by a government (or your house raided). Encryption keys are much harder to seize if taken care of properly.