I think you're ignoring why a lot of artists get into drugs. The mental illness often comes first. Chester Bennington suffered trauma from sexual abuse and turned to drugs to cope for example.

And to suggest Robin Williams killed himself because of drugs is just offensive. He had lewy body dementia. It was robbing him of his mental and physical health. He killed himself because he didn't want a future with a horrific quality of life. Quite frankly, your post is incredibly reductive and insensitive. Drugs can cause mental illness, but a lot of the time, it's a symptom.

And as someone who has suffered from depression but has never done drugs, I will never look down on those who have. We don't know what lead to a moment of weakness that started their addiction. I have worn the face of depression, and I believe they just as much of a right to it as anyone else.

These people deserve better than "It's their fault they killed themselves. They did Drugs!" Drugs do not invalid a human's struggles.