Deep movie if you can see it for what it is I think it showed how mental health can effect what we think is reality. And then we meet people suffering from the same things we do and not see them as bad people bc we understand them and think they're interesting. And then we take the drugs they give us bc we feel understood by them. And all of those factors (our own mental health, social reinforcement and a way to enjoy life thru a substance that a trusted person gives us) can cause an overdose. And that overdose feels like complete bliss. All the while, not knowing that in reality we are destroying our lives, end up homeless, breaking our relationships, negatively involved with the law and thru all that, still have no cure for the mental problems that started the cycle.
I imagine he was in complete, but experience an incomplete, form of bliss. It's like damn, in order to feel mental bliss we feel we have to sacrifice everything. Our lives and others. Until we go to rehab. But both rehab and drugs and relationships are temporary fixes of the underlying mental issues.