The government's job is to control everything in your country, they don't like the uncontrollable things, from the internet or the banking system, everything is monitored by the government and it is impossible for bitcoin manipulation because it is a decentralized system, in addition to the transaction is not taxed or disclosed personal information, it can lead to money laundering actions, which can damage the country's exchange rate ... so accepting cryptocurrencies is not yet possible, but I believe that in the near future the government will see how big the benefits of cryptocurrencies are and maybe they will amend laws to make cryptocurrencies legal.
Governments of the advanced countries to understand importance of cryptocurrencies and this is the whole reason why they are planning to launch their very own digital coins. They are the future of money and cannot be ignored. The reason behind resisting bitcoin legalization is fear to lose control. This makes a lot of sense. Like you have already said, authorities do not like to lose their power.