I think the government feels threatened because the government is very scared if this bitcoin or cryptocurrency is used as a tool for money laundering and for payment methods for terrorists so that the government is afraid of the dark side of bitcoin.
Yes this is also a reason besides so many others. Actually the government wants to impose regulations on the cryptocurrency and this is just because there may be so many side effects of Bitcoin if the people of the country start using it. Inflation might go out of control, and there might be uncontrolled unemployment.
Besides, the crime ratio can go high for transactions via Bitcoin do not have any record and this is why many governments feel insecure with Bitcoin and other coins.