If you're killing people that are no threat to you that's not just 'being different', that's wrong.
Yes, if we drop context and forget we're talking about killing people...
It's "wrong" because you believe that it's wrong. You believe that it's wrong because you've been taught that it's wrong - legally, morally, etc. But what if people are no longer coming equipped with the same moral compass or societal restraints as you, or I, or most people? If their reality - at a basic level - is that it's not wrong, then it can't be treated with medicine, and it shouldn't be defined as an illness. Their view of life, and their innate reaction to strike out at others that they perceive as a threat, or even just because they're weaker, could be a trait that's honed and altered and then passed on - like hair or eye color.
And the context is only there because you've added it in order to make it fit your view of the world - of what is right and wrong - based on everything that you know and feel. But context is perceived and applied differently by different people - just like one's moral threshold for what's right, versus what's wrong. It varies from person to person, depending on the person, depending on the conditions, and depending on the point in time, at which the situation is evaluated.
For example, strip away the context of the point in time in which this is happening. Line these incidents up in a vacuum against all other periods in world history. Do you think that more people are killed more violently now, than at other times in world history? Do you think that the people killed now are being killed for less of a reason than people that have been killed at other points in world history? The view of what's right and wrong has shifted - for better or worse - faster than humans can evolve. It took a couple of million years for humans to begin to walk upright, but we should expect that we can change our brain's wiring when it comes to killing other people (even "innocent" people) in a few hundred years - AND expect 100% adoption of these refined views?
Maybe even strip away the context that that everyone involved are humans. We're animals - maybe a bit more evolved in some ways, but still animals. The single biggest objective of all animals is to thrive and reproduce, right? It may be socially accepted that the definition of "thriving" is to work hard, get an education, make lots of money, buy land, etc, but what if other people have different definitions of "thriving"? What if a growing number of people are wired to perceive thriving as eliminating the competition. Other species of animals do this all the time. The kill competitors - not for food - but to help ensure their own survival, and the propagation of their bloodline.
What if the circumstances of the world that we inhabit today are such that a growing number of people can not compete to survive based on the "economic" definition of survival, but have adapted so that they are suitable to survive and flourish because they've gained a competitive advantage in another way: in their ability to overcome the competition? We're still animals, and it's still fundamentally about survival. Maybe the paradigm is shifting and the people that can't adapt are mis-categorizing the next phase in evolution as an "illness" or an "issue".