If I were the Fed's Chairman, I would be a lady, a tiny fragile yet very intelligent woman. I would not be afraid of Bitcoin, yet. I would dress up a project in corporation with NSA and FBI, let them inject some virus in the confiscated 170k BTCs and auction them to the greedy population. A year later I would spread the devastating truth and activate the virus. Bye bye Bitcoin. This costs not even one penny. Just a thought-experiment of course.
Someone would have to almost want to be infected. A public or private bitcoin address is not executable code. The metadata could provide a hash for such code, but couldn't execute it without some catalyst.