Myriad of reasons, control being one of the central. By ingesting substances, one can directly influence their inner world, and for many, that possibility alone

Myriad of reasons, control being one of the central. By ingesting substances, one can directly influence their inner world, and for many, that possibility alone is priceless. Additionally, most of the popular substances feel good on the short term. Alcohol, for example, lowers stress, and inhibitions in general, so it's easier to strike up a conversation, or to share a vulnerable secret and feel good about it, or to start dancing. So, drinking specifically is attractive in many ways, mostly short term. >Why would anyone with a brain poison themselves voluntarily? Getting back to this, some people also hurt themselves, with the specific goal of hurting themselves, or to attain something by it, or to give expression to their feelings. Specifically, I'm meaning self-harm here. And substance abuse can be partly done for self-harming reasons. And therefore it's very bad taste to assert that people doing this "don't have a brain". That's denying part of human experience, which no good person ever did in human history. Don't get me wrong, it's absolutely valid not to support people harming themselves, or to not understand, or relate as to why they are doing it. But since you see that many people are doing it, you can suppose that it's something you don't understand, rather than all of them being stupid.