Most people who use drugs do little harm to themselves or others. And as someone who has sold illegal drugs, I can tell you people sell drugs for many different reasons, not just as some get-rich-quick scheme as your TV-show-level analysis suggests.
Most of the people I have encountered over the years have sold drugs for money, or to feed their own habit. I'm aware that people dealers at the bottom don't make much money; although most of them think they do as they don't often have many better options.
