If we ever get to the point where a cryptocurrency is widely adopted and you can rationally say it represents something even vaguely resembling a global ledger, then overturning it would likely be very destructive.
There exists in society people whose interests are threatened by the existence of a universal, neutral, and incorruptible ledger.
Those of them who are aware of attempts to form one have very strong incentives to prevent that from happening by any means necessary.
Encouraging the development of multiple competing ledgers, either by investing in them directly, or investing in companies that produce them, or investing in propaganda to promote economic anti-knowledge, or investing in disruption tactics to slow down the development of the universal ledger are all actions such people could be expected to take.
Or likewise trying to suppress potentially-successful solutions to that problem by focusing attention and investment on the one least likely to succeed.