Nothing can kill bitcoin, but they can cause it to lose a lot of value . This may be possible if one of the major countries decides to ban it . But I don't think any country would want to do that . Because if they wanted, they'd do it already . Obviously, if we look at the marketcap volume at the moment, this is a very small percentage of the real finance sector . That's why bitcoin and other coins are not a big threat in terms of countries.