As much as I hate cryptocurrency as-it-exists, I'm very much into its potential. Untraceable (eg Monero) digital cash that settles instantly? That has the potential to disrupt societies. The problem is that most societies don't have a particular need of being disrupted, so people are perfectly content paying with their credit cards, and why shouldn't they be? The UX is better and the banks are fine as long as they do…
None of these things are good for a stable democracy.