As reference for my second post (re the Government attacking Bitcoin);
Blockchain.info reports the total network hashrate as being 184,000GH.
So, you'd need another 184,000 on top of that to have 50%. Then, account for all the other ASICs that are on the verge of shipping, lets call it that the government needs 500,000 GH to be reasonably certain they can shut it down quickly.
One BFL Jalapeno retails for $249 and provides 5 GH. You need 100,000 of them to achieve that much hashing power. That means at WORST, any interested party could pull off an attack for $24,900,000. But, wasn't BFL offering to sell their chips for $70 or so in quantity? So buying directly from them, eschewing cases, and such would bring the cost of the silicon down to $7 million. And that $70 cost likely includes a bit of profit margin not just for Butterfly Labs themselves, but their foundry too. At the end of the day, the gov't could probably go to a foundry and get what they needed for $3 or $4 mm. Even if assembly costs are $1 million, that brings the cost of attack up to $5 million.
Seems quite vulnerable if you ask me.... the ASIC's deployed certainly don't provide much protection against any "real" attacker, as much as people seem to think they do. And with all that said, the original question is "why is it not going up?", I'd now ask "Why should a virtual currency that can be attacked and nullified at a cost of $5 million have a market cap close to 200 times that?" Or, have I missed something?
Right. If some government REALLY felt threatened (pro tip: they don't) they could issue an order to a major chip fab corp (AMD/INTEL/broadcom or any of the smaller ones even) to produce a couple million ASICs at sub 25 nm. Our chip makers are tiny compared to the big guys.
Bitcoin remains fragile and at the mercy of these factories. So play nice, we aren't the biggest or even the smartest kids in the sandbox by a long shot. 500TH is a small datacenter and a couple months work if they want to break us. Its not like they can't, they just aren't.
If they did, it would expose that they are afraid in a very visible way. So.... It won't be the US, though it might be an "ally" that could do this.
The other option is to paint Bitcoin as Illegal druggies and gun-toting evil devil people, and then they can end us as a "public service". So... be nice.