Few here, maybe none, knew Hoffman personally. If you're feeling sad when someone you never knew dies you need to seriously re-examine who you're coming to feel close to. Actors' characters aren't them, but many who fall into this cult of celebrity make the mistake thinking they are. That they know these people. But chances are you didn't know the first thing about him, or any other celebrity. It's nice to appreciate, but when appreciation becomes delusions there's a problem.
In Hoffman's case, he died because he was stupid. At some point way back he had the chance not to try heroin or other toxic drugs but chose to risk it. Now he's dead because of that decision. Oh well. Are pleanty of people in the world to feel sympathy for who meet tragedy through no fault of their own. Feel sorry for them, but don't feel sorry for stupid people.