They may assume that if a lot of people use a drug, then it must be safe. The fact is, no drug known has a singular, harmless, positive effect. All drugs carry a price. Sometimes that price is heavy. Peer influence also plays a role with club drugs.
People are by nature social creatures.
If the pack is up to something fun, others are likely to join in. And the age when vulnerability to peer influence is highest is youth. Mix these factors together with high drug availability and the youthful sense of invincibility, and it forms quite a volatile package. So, prevention requires much more than just giving out information or providing water bottles at raves. It means tackling entrenched beliefs and attitudes, increasing social skills, and working to foster norms where drug use has little real attraction.