Parent should have more precisely said “over-activate dopamine receptors” instead of “run out”, but effectively it means the same thing — dulling an individual’s response to a set dopamine generating event via excess dopamine exposure.
Yes, it is a metaphor. Not everyone can understand neurobiology so we use metaphors.
Define Lacking: not available or in short supply.
Lacking (I did not say "run out" you did, again exposing your bias) dopamine is exactly what causes the symptoms of Parkinson's. It is well known that people with impulse control disorders are more likely to get Parkinson's.
Even Dopamine Receptor Antagonists increase addictive behaviors.
You are accusing me of all or nothing thinking but that is not what I am doing. But you seem to think that Dopamine has nothing at all to do with anything yet there it is in our body. It must do something, yes?