I'm going to give you the BoD and say that I think your confusing how addiction works and how the body regulates itself. Also, I should be more clear that anything causing an intense reward response can be addictive. Not just any old response will do, it has be a rush.

Addiction isn't just doing something repeatedly or enjoying something a lot. It's a progressive hijacking of the brain's reward system. It starts with an activity (like gambling) triggering a strong reward response. That response draws people to repeat that activity for the "high". If the behavior is engaged in regularly, the brain adapts over time. The reward response becomes less intense (this is what "gaining a tolerance" is), causing the person to to engage in the behavior more frequently or intensely to get the same "high" as they did the first time. Eventually, the behavior stops illiciting a reward, and you start to get stressed without whatever behavior it is that originally made you feel high. The person is no longer seeking the behavior because their reward system is telling them to, but for relief from the stress and anxiety of NOT performing the behavior. This is where addiction occurs.

Gambling, sex, and drugs all activate activate this feedback loop in the brains reward system. In contrast things like drinking water or wearing boots just just don't engage the reward system in the same way. You can experience this yourself by having an orgasm, drinking a glass of water, and comparing the difference in how you feel afterward. Drinking water and wearing clothes are biological necessities or habitual actions. They're not neurologically reinforced the same way that high reward activities like gambling or sex are.

I think we tend to prefer to think of chemical addiction as the true definition because of opiods like heroin. In the case of heroin, you're not activating your reward system so much as you're introducing a reward chemical WAYYY more powerful than anything your body can produce.

Other drugs don't replace dopamine tho, they just make your body release all of the dopamine it has at the same time, resulting in a similar, but less intense feeling. Getting addicted to these drugs is really no different, biologically speaking, than becoming addicted to a behavior.

Recognizing gambling as an addiction is not a slippery slope to naming more mundane things as addictions. It's the result of decades of work in neuroscience by thousands, if not millions, of doctors.

here's a quick cheat sheet of current DSM criteria for a SUD:

you need at least 2 to meet mild criteria (very easy to meet mild!) and 6 or more to be considered severe

so let's look at oxygen addiction:

we dont increase our use over time, we have no desire or failure to reduce use (even if suicidal it's not about the oxygen), oxygen requires very little time to get, we generally dont crave it cuz we always got it and without it there are no cravings anyway, it doesnt disrupt obligations, doesnt impact relationships, doesnt impact recreation, we don't put ourselves in dangerous situations just to use it, there's no medical risk to consuming it, and we do not build tolerance. we DO experience w/d. so 1 out of 11 aint cuttin it, sorry!!