Generally I agree, for certain values of "a lot of people" and with the restrictions of a given person at a given time. Fortunately, not all mass murderers are optimal mass murderers.
Very fortunately, there have been very, very few optimized murderers. The most effective ones use armies and countries or religions, while the ones who use bombs are many orders of magnitude lower in effectiveness.
Part of the lesson is that guns in the hands of citizens helps prevent mass murderers, even though it facilitates group murders.
A Ph.D student in neuroscience shot at least 50 people at a showing of the new Batman movie. He also appears to have released some kind of gas from a canister. Because of his educational background this person almost certainly knows a lot about molecular biology. How long will it be (if ever) before a typical bio-science Ph.D will have the capacity to kill, say,a million people?
Edit: I'm not claiming that this event should cause a fully informed person to update on anything. Rather I was hoping that readers of this blog with strong life-science backgrounds could provide information that would help me and other interested readers assess the probability of future risks. Since this blog often deals with catastrophic risks and the social harms of irrationality and given that the events I described will likely dominate the U.S. news media for a few days I thought my question worth asking. Given the post's Karma rating (currently -4), however, I will update my beliefs about what constitutes an appropriate discussion post.