Who is behind Bitcoin and what are their declared goals?
What makes them believe governments will not be able to stop the use of Bitcoins in the developed world if Bitcoins get significant traction? Is the goal to get traction in the developed world in the hopes of converting that temporary traction into a persistent presence (on smartphones since computers are not widely deployed there) in failed states and weak states?
(If it gets significant traction, I consider some first-world government's not wanting to shut Bitcoin down as so unlikely as to be not worth explicitly asking after.)
What government attack vectors against Bitcoin do you deem most likely to work? (There is probably a discussion thread on the Bitcoin forums on this matter.)
One obvious (and rather covert) method to undermine Bitcoin is to apply sufficient computational power before the computational power of honest users becomes prohibitive. This would permit a wealthy government to perhaps double-spend bitcoins, undermining the entire network.
An overt method would be to join, and then try to track down (via ISPs) the user associated with every public key.
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Currently Bitcoin mining appears to be profitable as only bubble economics can be. Already some Less Wrong users have purchased GPUs and started mining Bitcoin. Please consider sending some Bitcoins to SI at address 1HUrNJfVFwQkbuMXwiPxSQcpyr3ktn1wc9
2014 Edit: Please donate Bitcoin by using the Bitpay link on MIRI's donate page. Thanks!