There are reasons as to why government deemed it illegal, or, let us not say all governments because we have some that have come to embraced it and are thus using it as a tool to make something out of their battered economy. To such governments who are in the minority, Bitcoin is not illegal, but to governments who I think have a booming economy and have no reasons to use Bitcoin has a tool for economic recovery, Bitcoin is. And they have reached that conclusion largely to the volatile nature of Bitcoin which could make money laundering easier and wouldn't be traced.  One can not neglect the threat posed by these terrorist organization, with Bitcoin and its payment methods, you can't really trace how these lads are funded. And I think governments want to stop this money flow.