Working with those with mental illness has it's rewards. Many individuals with this terrible illness can be helped and will listen to good advice they're given by people who care about them, such as friends, family, and therapists.
However, with some folks with mental health issues, even the greatest and most helpful advice falls on deaf ears. It doesn't matter what you tell them. They don't listen to good advice and just do whatever they want instead.
Some people have to hit rock bottom before they can be helped. And sometimes even then they still can't be helped. It's just something you have to accept if you want to help individuals turn their lives around.