Heard this last week. Director of Stanford's Addiction program explains Dopamine production, action, anything pleasureful produces dopamine, but addiction is quick and receptors for pleasure same as pain.  Dopamine levels seek normal balance excess will be balanced by equal amount of discomfort,  ecstasy will lead to severe depression.  Karma is in the chemicals. Hope link is ok otherwise will post with author and books name.
https://www.npr.org/sections/health-shots/2021/08/25/1030930259/in-dopamine-nation-overabundance-keeps-u-s-craving-more