People use drugs for a variety of reasons. Here are a few:

To Experiment:

Especially for teens and your people, they are in that stage of their lives where they are pushing their boundaries and exploring new things. They may try a new drug or alcohol or cigarette just to see what it tastes or feels like. 

To belong:

Peer pressure makes a lot of young teens do things that they would normally not do. They want to show their peers how cool they are or impress them with silly behaviors. They want to belong to a group and that means they have to do what the group does.

To feel better:

Stress, social anxiety, and depression can make people use drugs in a bid to lessen such negative feelings. Temporary situations like the loss of a job, or a bad relationship can get people into alcohol abuse. People with health problems can also get hooked on medications (even if prescribed) to a point where they depend on them to get along.

To feel good:

Most abused drugs, especially stimulants are used because the user may experience a euphoric feeling followed by relaxation, pleasure, feelings of power, and confidence. Unfortunately, people don’t think about the risks of getting hooked and the problems that can come with its abuse.

To perform better:

Athletes and many competitive performers people get caught up in stimulant drug abuse when they use them to get extra power, stay alert, and chemically improve their performance. Coffee works similarly. People drink it to stay awake at work and at night to get some work done. It is illegal to use drugs if you are an athlete.