Is bitcoin legal or illegal in your country?
Because of bitcoin's decentralized nature, it has become almost impossible for the government to identify who are or who aren't using bitcoin. But I said almost because they can still somehow trace back the owner of an address and follow the strings.
Especially if you are using a centralized exchange, the chances of the government finding you has heightened. But if bitcoin is illegal in your country then it is most likely that centralized exchanges are banned as well. On the other hand, some people can still use bitcoin because they are very careful and discrete when making transactions.
That is exactly why they are not making it illegal, don't you think a nation who has their own currency, would make their currency weaker by allowing another currency to be legal there to be used? Of course they would, but they realized long time ago that if they put time and effort into making people stop using it, they could just tax it and make an income. This is as simple as that, they just realized that taxing and getting money from people is just a much better option.
This is why my nation not only allows you to invest into it and hold it, but allows you to accept it as payment too, not in some crypto way, not a special thing, you can accept dollar, euro, yuan, whatever foreign currency if you want to sell for that, and same goes for crypto in a manner.