To be clear, I do agree that a lot of cases of addiction will start with emotional problems getting people into prolonged consumption. However, emotional problems can also get people into obsessive running, yoga or whatever. But after getting their mind straight people generally don't need to be careful and abstain from running due to risk of a relapse of obsessive running --- contrast this with drugs, most prominently alcohol. Risk of relapse only happens with drugs, because it seems to my layman mind that it's not the emotional problems that get people addicted, but substance abuse. Emotional problems get people into substance abuse, but it's the substance that creates addiction, not the emotional problems, because see example with running.
And there are other triggers that get people into irresponsible consumption (societal expectations, such as in military[1]) that aren't emotional problems. They nonetheless often end in addiction, because of what the substance is doing to people's brains.
[1]: I'm talking about what I've heard from my father from Soviet era military about nicotine. I don't know what it looks like now/in other countries.
The vast majority of Vietnam soldiers who used heroin overseas did not continue using heroin after coming home. They weren’t using different kinds of heroin, therefore it is the person and not the material.