Why in some countries Bitcoin is banned is the accepting of Bitcoin by websites and that are illegal .
this is because they think bitcoin is illegal activities , they don't know about bitcoin that bitcoin is good thing
It is not just that bitcoins can be used for good things. But the transactions governments can't trace they worried that people can use for illegal things or to avoid paying taxes. Those reasons are valid ones. But in future they may come up with some regulations and start accepting these bitcoins.