B) It also seems unlikely since the type of person that would set up a bitcoin mining network probably believe in bitcoin as a currency, and thus wouldn't be willing to crash the currency unless it would hugely benefit them.
The kind of person running it right now, interested in the future of bitcoin. But that's like saying someone wont hack and ATM because you typical ATM technician wants to keep working at the bank. A hacker obviously is going to have different motives.
Well, its more like saying that the founder of a bank won't steal from his bank because he believes in it.
Now, if he screwed up and has tons of debt? Then yeah, he might steal from it anyways. But no matter what its a pretty big incentive not to.
The current law isn't really up to dealing with that type of theft (eg. defrauding people and taking their money, but using your control of the network to keep your bitcoins), but I have little doubt that they would fall afoul of at least one of the myriad anti-hacking laws, and that since they aren't the right type of criminal (eg. wall street), the justice system wouldn't overlook their actions.
Since the law is almost certainly behind the times, I wouldn't be surprised if they managed to get off scott free (after a few years of legal problems). And if they left the western world before legal action could be brought against them they probably would have almost no problems at all.
All that assumes they live in the US. Hackers with the chops to pull it off typically don't. There's probably like 2 or 3 countries tops that it would generate legal problems with, if any at all. And it's all anonymous to boot.
Unless the job had obvious ties to known enemies of the state, no state would even bother going through the process of investigating. Most official policies are along the lines of 'you do this at your own risk.' No major country has any stake in the success or failure of bitcoin any more than they do dogecoin or kanyecoin. Most that happens is they put out a PSA that effectively states "Only idiots would pay money for something with an obvious exploit that was apparent for years."
Exactly as Sheb said. One of the largest problems with charging hackers for things is finding out who did it, then proving it beyond a shadow of a doubt. If you know who did it (because there is only like a dozen people who
could do it, and it would leave huge tracks pointing back to their network) then they will probably be prosecuted.
There is also the issue of responsibility, it would be like twitter selling all their password data to hackers (and getting caught doing it). I have no doubt that the US government would be down on them like a ton of bricks, as would any western country. If you lived in Russia or China or the third world, you probably would escape trouble, but I suspect that the people (groups?) running the bitcoin mining networks live in the western world.
And finally doing this would be a huge huge thing. It would have a cost in the billions of dollars, and I suspect many goverments would take action just to be seen doing something.
Could they survive the lawsuits and avoid prison? Quite possibly, but they would still be persecuted in the western world.