I do not agree. I doubt the popularity of nihilism and similar ideas are causing a rise in antisocial personality disorder.
I imagine some people may feel like, if nothing matters, ethics do not matter. But (in my opinion) to feel that, the person was already non-altruistic and they only discovered that it was okay/justified to show it and to live by it.
In my case, I align to dark views about existence, but I also believe in the importance of taking care of others. If anything, believing that the world is unfair, senseless, painful, etc., has only made empathy/compassion and love more important (and urgent) to me.
What I’m trying to say is that I do not think our personalities and psychological oddities are so dependent on our views or ideologies. They can certainly affect us; for example, far-right ideologies can change a trusting person into a very suspicious one. But I’d say, in many cases, we are a certain way and we adapt our beliefs to that.
I would suspect a rise in narcissistic personality disorder, though. Narcissism is misunderstood. It’s not about thinking one is superior but about deep negative feelings about oneself that become a pattern of differentiating one from the rest (not necessarily in a grandiose way). Some studies use the term ‘vulnerable narcissism’ and that’s the presentation that I think we are ignoring as a society, so we don’t detect it, so we don’t address the possibility that we are exacerbating it. And vulnerable narcissists can be grandiose at times, and unethical, but most of the time they look like melodramatic self-fulfilled prophecies whom we brush aside as unwise or immature (think of many incels or edgy people or influencers caught in lies/dramas). And, even if a full disorder is not present, some traits can be. Perfectionism and unrealistic expectations, entitled rage, redirection or denial of responsibility, intolerance to shame, fixation on how one is being perceived (which can make the performance of an acceptable life more important than actually having a fulfilling life). It sounds like people I know and even myself in the past.
So… I don’t know about antisocial personalities. I do agree that they are more common than they seem, but I doubt we are ‘forming’ more by mere exposition to nihilism. Actually, facing nihilism seems inevitable, and our lack of a satisfactory response might be affecting our actions and societal values (we are all over the place ideologically, letting fascism get stronger and violence be normalized) which might cause the traumatizing and neglecting of children in a way that they are at risk of developing ASPD. But the culprit wouldn’t be nihilism. That’s only the question that we are failing to answer.
Our century is asking: “What if all existence is futile, what if our values are just our creation and all is senseless, indeed? Should we crave even more the material well-being and steal it from others, steal even their lives, in order to get it for ourselves? If not, what reason can be enough to justify stopping those who follow this? Is there something that may convince them to stop by themselves? What is the path we are choosing now?”. But we are not asking ourselves the questions, we are actually removing philosophy from high schools and universities and telling young people that only money is important…
And, don’t get me wrong, I think this is only a factor among others (climate change is pushing people into desperation, so it’s not only ideological but also a matter of material needs). Yet, I think we should be facing nihilism, questioning it, and not dancing around/inside it.
Sorry if this is huge…