Getting help for dual diagnosis adult child

Hello – My adult son (27 yrs old) has mental health issues (schizo-affective/anxiety) along with substance abuse issues (alcohol, marijuana, other stuff). He has been in and out of programs/hospitals for the past 8 years and is currently living in a rooming house with people who are alcoholics, crack and heroin users – not a good situation but it is all he can afford. I feel like I can help him get into what I think would be a better living situation for him like a group home/sober living house but he doesn’t want anything to do with any mental health/help and it frustrates me to see him living the way he is because he has so much more potential. He is a good looking, sweet, loving guy and talented guitar player. I get stuck between being a mother who wants the best for her son and “people are allowed to do whatever they want to do”. Where do I draw the line between figuring out a way to help him see his own potential for a greater life and/or letting him be who he is being, who is someone who wants to get out of his situation but doesn’t want the assistance of a mental health provider? Your coaching has helped me better communicate with him over time but I feel like I’m getting stuck with this. Any suggestions?