Of course he has weird thinking. Prolonged continuous drug abuse effects brain functions. It’s inevitable that his thinking is and will continue to be weird
I see you are denying that abuse of marijuana is one of the causes of his bad behaviors. You might need to read about it or talk to addictions counselors. It’s absolutely one of the causes of his behaviors, if not the main cause
Most people need to hit the rock bottom before they decide to seek help. As long as you provide him with home, food, bills paid and money to buy drugs he’ll have to incentive to seek help with his addiction. You make it comfortable for him to continue abusing drugs. Then you think he’d just randomly quit. He won’t