Bitcoin is not legalized in some countries for several reasons, mainly due to concern over financial stability, government control and regulatory issues.
What are the reasons why some government had banned or restricted Bitcoins??
It is a decentralized currency and that means the government won't have control over our transactions, the government only want the things they can control the way they like. Bitcoin's anonymity nature has also made it difficult for government to track and regulate its transaction and this has made the government to view Bitcoin as a threat to there control over financial system.