the existence of bitcoin is not a threat to jobs and national currencies because bitcoin is different than the currencies and so far, bitcoin is not to buy something in our real life and only available on the internet. and if people can get work related with bitcoin or cryptocurrency, then it means he can have another source income which can help him to make more money for his life. this is good for him because he can try to use his time to produce more money and he can make his life be better.
What do you mean not threat as a job? I know bitcoin can not be used to buy something in offline small market because its not known by many people yet among us. But threat as a job can be realized sinced many people already stop their job in offline just for doing this job.