People underestimate the neurochemical activity of AAS. They indirectly increase dopamine signaling by binding to neuronal androgen receptors in key reward-related brain regions.
This facilitates dopamine bursts tied to specific behaviors (like working out and strutting around in a string top, arms spread wide in a shameless display of ILS)
In other words, motivation becomes context-dependent. Dopamine neurons over-respond to particular triggers. As a result, the gym rat become more addicted to his gym rat lifestyle and Big Man identity, not to PEDs themselves (unlike stimulant drugs like coke or amohetamines, which produce massive baseline dopamine spikes)
Inevitably, the brain compensates by lowering baseline dopamine.
Responsiveness to natural rewards collapses when the drug is removed. Paired with joys of going hypogonadal, it's easy to see how addiction begins to lurk in the backround..
True. At the same time I've seen some guys transition well when coming off. Steroids in over HRT doses make you at least slightly tense and wired and I've heard a few say "wow I can't believe how good I feel now that I'm off, much more relaxed overall." Though a few months down the road many of them start to feel something is missing

Steroids can also mess with other neurotransmitters, GABA and serotonin, causing anxiety (e.g. boldenone messing with GABA, probably why it can cause severe anxiety in some). Since TRT became more popular and acceptable for docs to prescribe here, I saw other docs in the news warn that the initial kick you get from TRT doesn't last long and in the long run you feel worse. That's probably not quite right as a rule. At the moment TRT isn't quite physiological even in low doses because you don't get the natural daily fluctuations so it's not quite the same as natural production even if the tests show you are in the physiological range. And with TRT there may be a lack of downstream metabolites like DHEA and so on and all of it can affect mood. It's pluses and minuses

I'm using the Russian "actoprotector" bromantane to raise my dopamine in a "non-exhaustive" manner. It definitely works
https://en.wikipedia.org/wiki/Bromantane