I don't believe bitcoins is a threat to national currencies as they can co-exist with each other. Both function differently but they play their own important role.

But what I truly worry is that bitcoin is a threat for jobs. I've seen and heard people quit their jobs and just depend on bitcoin to earn their income. Now, I'm not saying this is bad, but if you think about it; If all the people joined the bandwagon they are not really conrtibuting anything to help the society.

Ah well. Not all farmers can be rich people, because who will plant the crops then?