I truly think it is because Haim was publicly known for his drug use for over two decades. Everyone could tell he was on a self-destructive path as Corey Feldman was at one point. Feldman chose to leave it all behind. Haim stayed with it.
I don't know if there is a good answer for this since I have a uncle who was on that path and was on the verge to self-destruct any moment. He turned to drinking, which damaged his throat and liver.....causing a lot of weight loss. He even stole his ex-wife's jewelry and other heirlooms, causing a lot of problems as well. He was near death until my parents took him in.
It is very hard for me to describe this, but we had to dish all alcoholic drinks away and had to make sure that he stayed sober for good. He had to go these meetings or we used psychology on him. Did you know how long it took him to not touch a drink......a year. It was exhausting. My parents were not physically fit to watch over since he is the youngest, so I had to make sure he did go to meetings and see that he was on the right path.
And this might be controversial for me to say, but I truly believe the person himself/herself has to be saved, but not by anyone. He/she has to be strong enough to know it was wrong and such. He/She has to make the choices, not family members or rehab workers. These addicted people(be it Hollywood or elsewhere) have to see their own mistakes and say, "That was shitty of me. I should have known better."
And it is very hard. Many will turn a death ear and not listen to you saying what they are doing is wrong. These addicted individuals won't believe it all. They have escapism and such. It is very sad and scary.....it is a path that is chosed by them and not by us.
To make matters worse, my uncle was surrounded by a lot of enabling neighbors that stole money from him and he was blind enough to spend it foolishly. Gambling, etc.
It is very bizarre and quite dangerous.....but if the individuals can look deeper at their mistakes, then maybe they can make a difference and tell their story.
It is not the best answer I have to offer, but that's the way I see it.
As for the moment now, my uncle is sober and has gained over 250 pounds. Finding a stable job he enjoys and making a lot of good influential friends in the process. No longer is the one that is drinking. Now, I see a very healthy man on the verge on doing something right. We almost lost him for such a long time.