If I were an entity such as the Federal Reserve or US Fedgov I would be extremely threatened by Bitcoin.
This is the point where your reasoning goes wrong.
Well, another point is, if you have enough to buy a lot of ASIC systems at retail price, that means you have enough money to produce them. It's not immensely expensive really, we did it as pseudonymous strangers registered on a forum with ASICMINER. Also, this way you could do it covertly, which would considerably increase the attack's effectiveness.
However that's not how State works at all. If it did, we didn't have hidden services, or even the Internet as it is. A lot of revolutionary things happened in recent centuries which could at the time may have been perceived as a threat to the State but then turned out to be as efficient to empower it. Bitcoin might very well be one of those things, or it might not be. Neither us nor the State knows how things will turn out. Furthermore, the State isn't a conspiracy of individuals, it has a mind of its own, and no one knows what it is thinking until it acts.