Crypto Currencies: Governments Will Figure A Way To Make Them Unsuccessful

As far as crypto currencies I don`t know. I know the theory and I don`t know why they would not work. My suspicion is that if they work, and they seem to be working, the governments are going to get very agitated because the governments like to have monopolies on money and they will do something to make them illegal or tax them. They will figure out some way to make crypto currencies not successful.