Yeah, good points, but Kaczynski tried to kill especially math or science professors or generally people who contributed to technological progress. He didn't try to kill as many people as possible, so detonating a bunch of school kids was not on his agenda.
Anyway, IMO it is odd to believe that there is less than a 5% probability that some psychopath in the next 50 years could kill millions of people, perhaps through advanced bio-technology ( Let alone nanotechnology or uFAI). That such feats were nearly impossible in the past does not imply that they will be impossible in the future.
Unless you believe distribution of damaging psychopaths is extremely fat tailed, lack of moderately successful ones puts a very tight bound on probability of extremely damaging psychopath.
All the "advanced biotech / nanotech / ai" is not going to happen like that. If it happens at all, it will give more power to large groups with enough capital to research and develop them, not to lone psychopaths.
In this video, Julian Savulescu from the Uehiro centre for Practical Ethics argues that human beings are "Unfit for the future" - that radical technological advance, liberal democracy and human nature will combine to make the 21st century the century of global catastropes, perpetrated by terrorists and psychopaths, with tools such as engineered viruses. He goes on to argue that enhanced intelligence and a reduced urge to violence and defection in large commons problems could be achieved using science, and may be a way out for humanity.
Skip to 1:30 to avoid the tedious introduction
Genetically enhance humanity or face extinction - PART 1 from Ethics of the New Biosciences on Vimeo.
Genetically enhance humanity or face extinction - PART 2 from Ethics of the New Biosciences on Vimeo.
Well, I have already said something rather like this. Perhaps this really is a good idea, more important, even, than coding a friendly AI? AI timelines where super-smart AI doesn't get invented until 2060+ would leave enough room for human intelligence enhancement to happen and have an effect. When I collected some SIAI volunteers' opinions on this, most thought that there was a very significant chance that super-smart AI will arrive sooner than that, though.
A large portion of the video consists of pointing out the very strong scientific case that our behavior is a result of the way our brains are structured, and that this means that changes in our behavior are the result of changes in the way our brains are wired.