Best friend and his girlfriend did LSD, the girlfriend had an immediate mental breakdown and was hospitalized. Diagnosed with schizophrenia in the following months, has been a life long schizophrenic ever since.
The best friend developed "schizoid personality disorder" over the next year and was never the same. Both were normal, happy go lucky teens that changed dramatically over a summer.
Another friend took mushrooms several times without issue, but one time had a breakdown afterwards and developed a severe anxiety disorder immediately after that never went away.
I could list about 5 other friends with similar experiences, but the point is, some people have extremely negative reactions to hallucinogens, and I'm glad I never tried them.