Most people that experiment with drugs don't become addicts, furthermore unless someone's head is completely up their asses, they know that drugs are addictive from a very young age. Making excuses for their behavior often enables them. In virtually all the help/rehab programs, a very important step is to take responsibility of one's actions and to try to stop finding excuses for destructive behaviors. Ultimately one can't be helped if they don't help themselves first.
Personally, I prefer to spend my efforts towards people I feel are more deserving of my time but I respect those who have the ability to empathize and work with addicts. I wouldn't nor couldn't do it for all the money in the world. There are people living in abject poverty all over the world who had no hand in their ply or kids actually wanting to achieve things with their lives, that's where my sympathy and efforts go to...
Certainly not for an overpaid pop star addict who managed to write and sing a few songs and strum a guitar...