It's uninformative to conflate monetary policy with the underlying material/technology used for currency. The two are totally and entirely unrelated. It's like claiming that changing from paper to (still fiat) coins is good because this would cause a fundamental shift in the nation's purportedly destructive monetary policy and also paper rips which is a bummer. So coins > paper, clearly.

Which is to say, you are really making two totally independent claims. One is at least plausible and the other isn't.

The first is that bitcoin provides a viable alternative to current methods for exchanging fiat currency. This is probably the most sensible argument for cryptographic currency, and I think is worth discussing. The discussion below delves into some specific arguments on this issue.

Your second claim is that decentralized cryptographic currency will or ever could/should replace state-backed fiat currency. I don't think this is a particularly useful point to discuss, since informed prediction is impossible and the prescription mostly amounts to political persuasion.

edit: but also, the US could switch to a cryptographic currency with all of the practical benefits of bitcoin, and still retain basically the same amount of control over its currency. Technology can never solve big political problems.