What do you think about me telling my friend's parents that he smoked got drunk and took drugs?
Why would you tell your friend's parents about those things?
He hides it from them.
I know it may be a situation where trying to look out for your friend. But if he is using these in moderation and not a danger to himself then I don't think will be any point to telling his parents this.
I don't care and I want him to get it. I think he will thank me later.
It's understandable that you want to stop your friends from abusing drugs and alcohol. However, you may complicate his life by talking to his parents about it. It's best to talk to your friend about your concerns.