The argument about the use of cryptocurrencies in money laundering and other illegal activities is partially true, but is a red herring. There is also a serious effort on the part of the financial elites in government and academia to ban cash as well, who make the same argument that cash is used for criminal activity. Bannng cash and cryptocurrencies would be a way for governments to gain more control over their citizens and monitor their every activity. It would also allow governments to do things like impose negative interest rates to coerce their people into spending if that's what the government wants them to do. Negative interest rates have been imposed in various countries but have been totally ineffective, in part because people and corporations can hold cash and other assets like gold to avoid losing money via negative interest rates.