Counterpoint: I have done quite a lot of DMT and 5-MeO-DMT and they were both fun and interesting substances.
My advice is: Do not stay away from drugs unless: a) that is your personal preference, b) you have a specific medical issue that precludes being able to experiment with something safely or c) you are not curious enough to educate yourself thoroughly about a substance before trying it out.
HPPD is wildly exaggerated by almost exclusively people that have a vested interest in policing other people’s behavior and values. Belief in the dangers of “the ability of any substance to permanently change your brain in a negative and nonspecific way” (a hilarious logically impossible supposition) almost always follow up with “don’t do drugs, instead do what I tell you to do. Read my self help book or convert to my religion. My values are the best values.”