The decentralization of cryptocurrency is an important reason why it is difficult to legalize.
The banking system is managed by the government and can control funds, and the government can also profit from it. The cryptocurrency is not subject to government supervision, and the funds are completely controlled by the user. It is difficult for the government to manage fund data and information, so cryptocurrency is easy to be used for some illegal and criminal activities. The government will also worry that using cryptocurrency to launder a large amount of money is not conducive to the national economic interests.