Wellif you examine the block chain you can see the attacks that were being made against mt gox.  I watched it happen from my blockchain.info account where they know what they're doing. 

The reason "they" can't shut down bitcoin is because it is decentralized.  The government won't round up all the bitcoin mioners and put them into concentration camps.

Also, no one has mentioned that a mature bitcoin has a very good chance of bringing additional stability to the global economy, imagine SDR's but for people, not just central banks and nation-states, but free of corruption, an incorruptible store of value, and a huge boon to those in the third world who will finally have access to investment capital and a safe, stable currency that isn't run by a war-lord, and inflated away every time he starts a blood feud with another tribe.

I think we can all agree that bitcoin will change the world like the revolutionary innovation that it is, or it will crash and burn cause it's a flawd concept hyped by some tech nerds who don't truly understand economics and monetary theory.