Earlier quoted context omitted.
This type of empty fear mongering comment is unhelpful at best. It's a McDonalds of a comment. What's a lot of people? Why are psychedelics so special compared to anything else (sugar, Facebook, gambling). "It doesn't happen to everyone, but it's common" - what does this even mean? "Common" based on what criterion? How should our behaviour as a society change based on your comment?
Psychedelics can definitely trigger or exacerbate mental health issues. A few years ago my group of friends lost someone to schizophrenia after he started micro-dosing LSD daily. I've tried many of these substances, and know people who have gone a lot further, so I'm not speaking out of ignorance here. There are risks to these things, and it's not a positive experience for everyone. Giving people a warning about that…
It's like saying "driving in a car is dangerous, and many people art hurt every year doing so." Okay, so what? Are you saying everyone should stop driving? It's just not useful - compare it to something like telling people to wear a seatbelt or pointing out that driving in particular conditions is especially dangerous. Those are things that we can use to drive more safely. Saying vaguely that driving can be dangerous doesn't serve any useful purpose.