There really is a difference between someone who uses a substance and someone who is addicted to it.
I like alcoholic drinks (beer, wine and the occasional mixed drink) and sometimes get mildly "drunk" but I don't drive after drinking, and my personality doesn't change negatively to affect others. I can go for relatively long periods without drinking and I don't crave it. I'm 82 and recent tests have shown me to be in good health. On the other hand, some people are truly addicted to alcohol and it ruins their health and lives.
I have no interest in gambling, I find it boring. My father would gamble small sums on horse racing, but it never went beyond that and I think he pretty much broke even on it. He enjoyed it. Some people allow it to destroy their lives.
Some substances seem to be so addictive that it's virtually impossible to use them in moderation.
The term "addiction" is misused a lot of the time. I don't think it's correct to call someone that spends a lot of time on the Internet (for example) an addict.
I think many people who do a lot of running for exercise are addicted to dopamine, but we don't seem to consider them addicts.
What's my point? It's a complicated subject.
I've heard the term "gambling addiction" used quite a bit, although I agree that it sounds like a misnomer. Still, the meaning is pretty clear. It's kind of like how people use words like "workaholic." Are people actually addicted to work?
I think the term "compulsive gambler" is also used. I've also heard phrases like "sex and love addicts."