So the only way to make money on this attack would be to short a very significant amount of bitcoin. I don't know it that would be illegal - does it count as insider trading if you cause the value change?
So the mining costs do not have to cover the entire value of all bitcoins. They only have to be large enough to discourage political attacks, and large enough that a bet to short twice the mining costs worth of bitcoins would be noticeable.
Still, it's an interesting point that I haven't seen raised before.
EDIT: woops, other siblings of this posts are right. The protocol validates all chains before accepting the longest one as true, so you can't print or steal bitcoins even with 51%
More importantly, what gains would the attacker get to compensate an expenditure of such big amounts of money?
Anyway, the secret service and possibly the FBI one run anti counterfeiting operations so it's slightly higher than that. Beyond that, I think there is a fair amount of diplomatic operations that support the USD but it's still far far cheaper to run relative to value than bit-coin right now.