opsec
Though not impossible, it's ridiculously hard for people to manage all sorts of endeavours securely. Not least since today's widely used overlay networks are all still subject to Traffic Analysis and Sybil. Regardless, they are meant to provide end to end encryption and other abstractions that are helpful to privacy. People have a hard time keeping even their central Fiat bankcorp accounts secure on their phones. And while they can choose central FiatCoin cryptocurrencies, same problem there. Then there are all the bugs in even opensource wallets. And lack of UI, training, etc. However reasonable security is possible. It will be interesting to see what fraction of people choose the distributed "be your own bank" and mining model of real cryptocurrencies. That is up to you teaching and showing them the way. Otherwise there is no point, just stay with FiatCoin.
tumble the coins
Those exist. Yet one area that still hasn't seen any significant entrants in the network overlays are non-fiat cryptocurrency exchanges. At least until true DEX's hit the scene, and though they would be central points, there could easily be be any number of such exchanges running there. They actually serve good and very legitimate purposes... So that spending cash for a can of soup doesn't disclose other purchases, clothing, fuel, gifts, etc, or your financial positions to others, not least to protect you from becoming a theft target. True privacy coins will take that function over from weaker methods. And for simple exchanges where needed, just as tourists do today at any corner market, Yen to Euros to a nice dinner. This function will always be needed, and should be just as private. All coins that do not utilize cryptographically strong privacy are lesser in function and adoption potential and utility than even the Metals and Fiat cash humanity has used since time began. They are an affront, an oversight, a mistake. Today with ZK Proofs, strong coin mixes, overlays, TLS, etc, coins that fail to implement at least some privacy methods, even if default on with selectable off, start to look really suspect and totally irresponsible to their users... they're offering less than Metals or Cash do... thus are shitcoins, and should be publicly called out for it. Privacy is a basic human right for all, required for humanity as we know it to function. These services and privacy coin capabilities need to be created and widely adopted throughout the cryptocurrency space as soon as possible. Without it, you'll lose the historic chance you've been given, and be stuck with FiatCoin forever. It should be obvious how badly that would suck.