People get the idea that if someone touches drugs, they instantly have no future. This is far from the truth. Many successful people do drugs. Actually, MANY people in general do drugs.
That doesn't mean drugs are a good thing...but it doesn't mean that they are bad. Basically, People do drugs for the high. It's a great feeling. Some people also do it to relieve stress...or as a temporary escape from problems. Of course some drugs are worse than others...but doing certain drugs in moderation isn't always a bad thing.
As I said in a thread similar to this (in the arcane sanctuary)...
There is a difference between a drug abuser, and drug user. Smoking a joint every once in awhile to relax, or just have fun won't mess you up. I can garantee it (unless you have some wierd alergic reaction). Now smoking weed day in and day out can eventually lead to problems (mental, and physical).
This goes for almost anything.
Food for example. You can eat at mcdonalds every now and then, and be fine. The fat in the food won't affect you. Now you can eat their every day, for every meal, and become fat. Soon you will get health problems, and possibly die from complications.
So, I'm sorry to burst anyone's happy bubble of love, but using drugs isn't always such a bad thing. I know allot of people who smoke weed, and have great health, and grades in school. I also know some pot heads, who are losers. There's a huge difference.
But anyway, your question is pretty obvious. People do drugs for the high.