Even though I like decentralized currencies, unfortunately, cryptos only exist at the mercy of centralized governments who use fiat. The internet infrastructure that crypto relies on and physical businesses that take crypto all exist within the territorial confines of centralized govs who enforce and regulate it with military force. So far cryptos have been allowed to exist as sort of a cute experiment, if they ever get mass adopted to the point of causing a noticeable dent in taxation, the gov will likely crack down and ban the usage and mining of cryptos by people, businesses, and sites that reside in its territory. Even if crypto servers were setup in antarctica to avoid centralized govs it would have no military backing and could get crushed in an instant by a willing central gov, and the only way to avoid that would be to get their own enforcement power which ironically would make it centralized like every other currency.
Furthermore there is nothing proprietary about a specific coin, even bitcoin, whose technology can easily be duplicated as a ton of copycat coins and shady ICOs have sprung up recently. the only thing that keeps it as the "main" and most liquid crypto is its brand name and popularity, whimsical aspects that have no real military power of enforcement in case real world stress tests starts.