The only thing that i see danger in cryptocurrencies is the government because if the government will not agree in using cryptocurrency then if they will ban it then our hard work will turn to nothing so i think it is better if we make using cryptocurrency legal first so we don't have to worry about because the coins are legal and the government already approve it.
I dont see a reasons as of now that Government will ban such cyrptocurrency and I dont see it as a danger. As from what I have observe the danger is in bitcoin on how the government can impose the tax. I think the danger may arise if bitcoin can be legalized by the government and bitcoin will more used than fiat.