The Best Attack is for them to simply buy 100s of billions worth of bitcoins in a short amount of time while giving it massive amounts of positive media attention.
Of course they wouldn't get a return on their investment, but its not about money it's about power.
Here are the results:
1) Current bitcoiners (very small population) would be so overcome with their wealth that it would be almost impossible to focus on improving bitcoin.
2) Bounties would cease to exist entirely or become very rare.
3) The huge spike in price would attract the whole world to get involved in bitcoins causing the bitcoin price to continue launch to high heaven.
4) it peaks
5) We watch a gradual price decline for the next several years with one negative news report after another (remember: they own the media).
6) This new wealth attracts every schemer, con-man, and hacker in existence to attack every bitcoin web site for personal gain - which is easy considering most of the services are new and vulnerable.
7) All new bitcoiners (which would be very large portion of the bitcoiners population) turn very pessimistic and negative towards the project and slowly give up one by one.
The media circulates stories of how it is the money of drug lords and terrorist and start rumors of legislation.
9) Thank goodness "Bitcoin is dead and behind us" attitude - it was just a fad.
10) It lives on as niche-techy-nerdy currency that has little chance of rising again to challenge their systems - they just ignore us from then on.
Sound familiar ?!?
Thank god for the incremental halving of the block reward
