Addiction is sometimes described as something that is done repeatedly and is harmful. I can't get by without breathing, so I need to do that pretty often, but as it's not harmful, it's not an addiction.

The answer to your question is it depends... I don't think there is anything wrong with playing a dopamine hitting game on a 10 minute bus ride home from work (it's no different than the buzz from a shot of espresso), but if you are spending so much time that you are harming yourself (physically or emotionally) then that's an addiction.

There was a talk posted a few days ago here by Dr Gabor Mate about addiction:

https://youtu.be/vMstO3U4sVw

(Skip the 10 min intro, then watch at least the first hour)

His views are very different from the mainstream US view of addiction being substance abuse that can be fixed by restricting access to the drugs.

Listening to music is essentially a drug in that it releases pleasurable neurotransmitters. I think we need to understand the positive and negative impacts to ourselves like you suggested.

I don't think so--if the activity fits your life and not the other way around. But that's just my opinion.

Books and pen pals can be similarly problematic for some.

I don't think I've ever acquired deep knowledge or insight via my phone. It's all shallow junk food.

Is that because of the nature of the technology or because of what users choose to seek out with it?

Also consider that a big insight might come from many small insights