Also, seeing as putting rats in cages alters their psychology so much, doesn’t that mean that other experiments could be skewed ?
Some people want to destroy themselves, and are going about it under the guise of addiction. Some people want to run away from their lives, because their lives are filled with so much pain. A lot of people started using because it was a way to connect, to be social. Not until they were using heavily did the drugs become a problem. The two drugs causing the most death and destruction are alcohol and nicotine. Both are considered socially acceptable, and alcohol is actually encouraged as a way of being social.