Look using any kind of hallucinogen unwisely can lead to bad trips. But permanently scar you? Im not so sure. I think theres a lot variables at play there. Much more than just drugs.
The simple fact of the matter is the true amount of mental preparation you need to go through before your first trip is more than you will do. It's simple luck that the vast majority of people that trip for the first time have fun. The Catch22 is that you can't be prepared for a trip until you've tripped. Hallucinogens will be the greatest difference from your Self you'll ever realize. And people should always recognize that. Do that and you won't have to worry about anecdotal stories about taking to much LSD and going "insane"