Somewhere, a group is preparing an attack on Bitcoin. It will come around the next big pump. The attackers will have an exponentially large advantage of computing power. If the network isn't compromised, it will be severely damaged.
What you are saying is not an easy thing to do, none can really launch an attack on the bitcoin network it self, and even they will they would need a tremendous amount of computing power, some time ago i read a post on how many computers does it take to mine 1 btc and the answer was 50 billion slandered cups, so imagine how much more to crak the whole network, if there is someone who is able to do such thing is the government and that is in order to take it down and remove its threat on the fiat situation.