all of this aside, I think if the NSA had the ability to disrupt the security model of Bitcoin's fundamentals, they would have done it by now. Unless it is just a massive project to crash the world economy, force everyone onto cryptocurrency and only then start pwning the private keys of people they don't like.
There is a very simple reason. Bitcoin was created to be a substitute for gold. The US government has a lot of computing power but run out of gold. They owe a lot of gold to other nations but will never pay it back in gold.