A classic Hollywood trope is the evil genius madman who is using new technology he just invented to murder (or blackmail with the threat to murder) a large chunk of humanity. Always the lone evil genius works in a high tech haven, hidden from others, all by himself. At this point, the scenario is total fiction because no one can run all that technology by themselves. It is hard to keep 3 computers and a network going all by yourself. The madman's electronic door hatch probably crashes once a month, particularly if the madman just invented it. So can you invent and keep operational the death ray? No. Way. No solo genius can destroy mankind. That kind of power takes cooperation.
In fact, I offer a new theorem: The power of an individual to kill others has not increased over time.
To restate that: An individual -- a person working alone today -- can't kill more people than say someone living 200 or 2,000 years ago.
At first this seems to fly against all the other trends in technology, but I think this law is true, and it is true for the same reasons that overall violence is diminishing over time, as Steven Pinker points out.
I did some basic research to see if my hunch was correct, so I asked weapons experts about the kill power of solo weapons. How many enemy can they kill by themselves? I did not find any weapons that moved the number out of the ordinary order of magnitude of 10^2 people killed. That is a person can use old technology like fire and poison, or sinking a boat or airplane to kill many hundreds, and new technologies like drones or machine guns also give similar results. It turns out it is hard to kill thousands even using modern technology.
If I were doing proper research I would go through news clippings about deaths per deliberate act by a single person, to see what kinds of body counts mass murders have accumulated in the past. I haven't done that but at the same time I don't recall any mass crimes where one person killed thousands by himself. (If you know of any, can you email me with a source?)
While I am pretty certain this trend holds true for individuals, it may hold true for teams as well. This is trickier to prove because of defining where teams end. For instance 19 hijackers killed 3,000 plus people in the 9/11 attacks, which is at most 150 killed per person involved, and much less when you include the many more Al Queda leaders and support than just 19 hijackers involved.
I suggest you'll get similar numbers if you take the number of deaths per team member for mass killings. For instance there were between 100,000 and 400,000 people who died in the atomic bombs at Hiroshima and Nagasaki. The Manhattan Project employed 130,000 people, so that ratio works out to be in the neighborhood of one person killed per one person involved, and certainly no more than 10.
I think there are two reasons for this effect. 1) People are hard to kill, and the greater number you want to kill at once, the more complex it becomes, requiring much more social cooperation. The totally false myth is that a lone rogue bad guy can kill everyone. And 2) More social cooperation also generates more social resistance, making it more difficult to recruit resources for the project.
We COULD invent a mass people killer that would allow any single person to strike down more than thousands of people, but the financing, and engineering needed would be subject to so much social pressure against doing that, that it has not happened and probably won't happen. The engineering problems are formidable: how do you make this weapon "safe" until it is triggered, and so on. The problems of a safe weapon of mass destruction is one reason I don't buy the idea of a rogue scientist making a lethal bio infection, a la a Small Pox mutant. Again this kind of achievement is very hard science to do; you have to keep testing to make sure it will work (but how do you test by yourself?), and all without killing either yourself or your loved ones. Can it be done? Yes, but not by one person. You'll need many smart people, and money, and both of those come with built in forces acting against the idea.
It requires a lot of power to kill many at once. How about you ignite a nuclear bomb in a sports stadium? That would kill a lot. But the truth is this is very hard to do by yourself. Getting a bomb, and getting it to ignite when you want it to is not easy. Do you know how to arm a nuke? That info is not on the internet. The more powerful a tech is the more people you need to operate it. The more people you need to operate it, the more resistance it will gain against using it to kill.
If those constraints are true then what about subverting an existing technology, already developed, and weaponizing it? That was the genius of the 9/11 hijackers who weaponized a plane into a bomb. (But even they did not achieve a higher kill/killer ratio.)
The lesson of "what technology wants" is that any technology can be weaponized, so this idea of subverting existing technology would seem to fertile ground. While it is not hard to weaponize a technology to be a chronic low-level killer, I think our society is built for the purpose of making it hard for technology of any sort to kill us massively. We do everything we can think of to prevent it from being dangerous as we deploy it. We are very sensitive to this possibility of bite-back, and as the technology is being realized and refined we are removing as many options for mass destruction as we can. We do that in simple ways like where we allow them to be built, or stored, or used. For instance things that can explode we keep far from homes. Drones are now going to go through this process in the coming years. Weaponized drones will be able to kill hundreds, but society will work to prevent them from being able to kill thousands or more; and if they can kill thousands, that will mean hundreds of people will have worked on them and operate them, not just a single person.
Well what if an entire country or tribe decides it wants to collectively use technology to kill a lot of people? That happens and it is called war. But as Steven Pinker has proven, the physical violence of war -- the number of killed per event -- has been diminishing and continues to diminish over time. I have not made the calculation but I suspect that the kill/killer ratio in war has been dropping and will continue to drop even as the remaining war becomes higher tech.
The myth of the lone evil genius is that you can make complex technology all by yourself without the infrastructure of a society. You can't, at least in the beginning. Because more powerful technologies require more social support, this increased social pressure keeps the technology in check. Crazy rogue geniuses with caves full of death technology ticking down to blow up the world make great villains on the big screen, but there is no evidence at all in the real world that anything like that has ever happened. (Correct me if I am wrong.)