The government is just trying to protect its people from being scammed. In some countries despite the warnings from the government to citizens not to invest in Ponzi they went ahead to invest which many people later regretted their action, so the government is afraid that its people may be scammed as a result they are protecting the interest of her people.
Bitcoin is not a scam and governments are just corrupted that's why they are banning cryptocurrencies in other countries, another thing is that, government is also afraid of losing people to work on their companies.