After some amount of different hallucinogens he became lastingly weird. He would start saying things about "divine geometry" and "seeing yellow auras" when he closed his eyes and became a big believer in all sorts of supernatural (e.g. horoscopes)
He did come back to something not too far from normalcy maybe 8 years later, last time I heard from him.
Normality is a broad but pretty well-researched subject and i think it's safe to say, belief in horoscopes and other unsubstantiated supernatural phenomena ain't it.
In that way, "normality" is flexible: if you change your behavior in a consistent way, your new behavior is normal by that definition. You didn't become "abnormal" you simply redefined your normal.
Now the article goes on to mention that you could also define this relative to a larger population, etc, which supports your point - but the very fact the headline definitely doesn't align with your claim shows that this is not as straightforward as you make it out to be.
But I for one feel everybody around me finds "weirdness" unbecoming. I find it to be an inescapable reality that people will care about you less and not want to get you for any manner of tiny deviation (e.g. as an extreme example, just if you said "beep" outloud every 10 minutes this would be reason enough for I think half of the population or more to not want to associate with you)
In my friends case though, I think what scared me the most was he became very unclear/metaphorical in speaking about even basic topics and didn't seem to realize how much trouble people had understanding him.
I want to demystify this a bit. I don't think it's as unusual as you suggest.
I assume you haven't had any substances lately. What do you see when you close your eyes? If you're like I've always been, you see floaters, a few spots of light here and there, maybe a faint "ghost" of the image your eye had seconds before, especially if it was bright. I first noticed that in childhood. In childhood I also noticed that in low light, like in my parents' car in the evening, I would see this light occasionally. I read in some places that this is a possible explanation for when kids complain about seeing monsters in the closet, or similar. As I got older I noticed this sort of thing less.
Later I started getting migraines, though, and when I get those symptoms I also see light that isn't there. Sometimes when I have a headache I can see it come in waves when I close my eyes.
Later still, I got a little into meditation, and I noticed I could make those perceptions come about by manipulating my breathing.
And finally, I did a low dose of psilocybin exactly one time in my life. I saw colors when closing my eyes. It was pretty much the same as all those experiences above, only a little more intense.
But you know, we also see faces in clouds. Sometimes we think we spot recognizable objects, then look closer and longer, and they're not there. Our brains are taking shortcuts based on limited data all the time, without drugs. What the drug does, in my layperson's understanding, is make your brain very eager to make these connections. Just as you might see a face in a random, noisy pattern when you're not looking closely, your brain is eager to interpret whatever visual data it gets and run with it. When your brain is deprived of sensory input, such as in darkness or with eyes closed, seemingly it can do this more.
I would say about your friend, don't rush to judge them for describing a particular wrinkle of how his brain works. Perhaps they got a little too into talking and thinking about it, or came to the wrong conclusion. But the experience itself is not that remarkable, and happens to sound-minded people all the time.
I would recommend psychedelics, but like anything, it depends on the person. There are dangers, but those dangers can be controlled quite well. At the population level, it is safer than coffee. At the individual level, it varies, just like anything else.
I will note that after taking ~110 μg of LSD-25 on several occasions, my overall cognition improved dramatically.
I have eye floaters and I can live just fine with them jumping around, still doesn't change the fact they are annoying and if I could get rid of them I would; if they were caused by something I did and I could change that, I would.
I'm sure most people with HPPD, if given the choice, would never have done psychedelics in the first place; HPPD is why I stayed away from psychedelics.
My understanding is that many spiritual traditions have historically viewed psychedelics as ego’s way of “grasping” for enlightenment, for many before they are prepared for what they may experience.
A “bad trip” can leave someone in a state of confusion that they aren’t quite prepared to deal with.
Here's an interesting post about it maybe being due to extremely high "openness" caused by psychs: https://slatestarcodex.com/2016/04/28/why-were-early-psyched...
I suspect this is much more common than anyone realizes: https://slatestarcodex.com/2018/06/06/hppd-and-the-specter-o...