I think bitcoin cannot ruin a country but technology makes the country to convince about it. Already governments are majorly focusing on developing this new technology in order to get more awareness about their daily usages. Because this technology is making more convenient in many ways usages.
Instead Bitcoin gives us an opportunity how to do business on line and how to invest. The reasons in my country forbid are in order to implement the principles of prudence, safeguarding business competition, risk control, and consumer protection. many parties are biting the bitcoin into gambling and the government protects the consumer's right from theft.