If cryptocurrencies are fully outlawed, there's nothing great for any market, because why would people risk going to jail or paying a huge fine over simply trading? They would just go back to trading stocks and other instruments, and those who want just a store of value will buy gold or the US dollar.
Don't underestimate people. China has made the practice of exchanging Bitcoin (or any other crypto) to fiat illegal by law, yet the local markets there count millions upon millons of traders who are still involved. In other countries the reaction to a ban has also lead to a massive boost of local trading volumes. Once people get involved, they mostly don't go back.
Hard drugs are a great example of how fully outlawing something doesn't help. In some countries using/owning/selling/buying hard drugs leads to a death penalty, yet it happens continuously. It's a global market worth hundreds of billions and growing rapidly despite how every single country is doing what it can to curb that growth and come up with even harsher penalties.
Prohibit something that people like or somehow need, and they'll go there where you don't have much oversight as government to get it.