how do you deal with watching someone you love self destruct?

I often refer to this quote.

Sometimes being a friend means mastering the art of timing. There is a time for silence. A time to let go and allow people to hurl themselves into their own destiny. And a time to prepare to pick up the pieces when it’s all over.

Usually when it’s happening your loved one is aware to some degree what they’re doing. But trying to correct them never works. They have to make that conclusion themselves.