Imagine having the worst flu you’ve ever had. It feels like you’re dying. And there is literally only one thing that will help and taking it will instantly cure you.
You’re going to do what you can to get that thing. It’s a difficult urge to fight, especially when it feels like life or death (and in the case of alcohol and benzos, it can be).
Your body dictates that you do things all of the time… You can only hold in your piss and shit for so long before it starts to harm you. You need to eat food. You need oxygen, and cannot hold your breath until you die. Your body has tons of “reflexes” that cause you to do things outside of your control all of the time.