I went through an addiction myself and I agree with you.
Emotions are not super well understood, and I think they are at the root of addiction. If you are chronically unhappy, drugs let you feel good. You start feeling better because of the drugs, and lose the ability to respond to negative emotion in a healthy way. Healthy emotional balance lets people make good choices and fix bad problems. Being chronically unhappy - perhaps as a result of unresolved mental injury - will hamper a persons ability to make good choices, just like being keep in darkness for a log time will make your eyes way too sensitive to handle normal light.
Show me someone who is addicted to drugs, and I'll show you someone who is unhappy about something other than the drugs. The addiction just makes the underlying problem worse.
If you can learn to fix the underlying problem, then fixing the addiction itself is much easier.
Once you are knee deep in drugs, your life becomes awful which gives you more reason to keep using the drugs. It's like a local minimum, or an AI that learns to manipulate it's model of the world, because that's easier than manipulating the world itself.