Advantage:
Cryptocurrencies offer various practical merits over more fiat money as well. For instance, citizens of developing countries may find it challenging to locate a currency with any value in the global financial marketplace. This would mean that such a populace will effectively be locked out of the global financial system. Cryptos  with universal access   such as Bitcoin would open the global market for such people allowing them to participate in the worldwide economy.

Disadvantage:
On the other hand, cryptocurrencies serve no practical purposes in the contemporary marketplace and have nothing underwriting their value. As such, it is theoretically impossible to assign a value to them apart from the fact a few users have accepted to use them as currency or token and the usual economics of demand and supply.