Yes to all of the things that you listed, I think.
For some people, if you have a risk of developing a mental illness and you also use drugs and alcohol, your risk of manifesting that mental illness goes up. Once you then have the mental illness, the risk of it being worse in terms of its course and outcome is raised by ongoing drug and alcohol use. For some people, drug and alcohol abuse and dependence arises as they self-medicate for low-mood, post-traumatic abuse problems. Aspects of psychosis that some people can self-medicate from results in worsening of the course and outcome. They're not only having the core problem they had to begin with, but now an addiction problem on top. There are other people for whom the problem is a primary addiction one that results in secondary mental health problems as the rest of life tends to decay. So I think all of the above are pathways, and in each individual case you need to—