Besides the obvious disadvantage of betraying my friends, should I report instances of drug abuse to the police and local authorities?

I’m a bit angry that drugs can cause so many problems and how easily people can buy them and get away with using them. It seems to be destroying their personality and preventing them from having success in the future. I want to change this, but I’m wondering if reporting marijuana, drug use, underage drinking and smoking, etc. to the police would be a lost cause.

Would this even be the right choice? How would one even go about doing this? Finally, would it solve problems in society and possibly in the drug users’ lives?