Why?

> but Hoffman was so respected and loved. Why would he start with drugs to begin with? (forgetting being trapped by an addiction)

Well, first, you assume that he started drugs after he was "so respected and loved", which may well not be the case, and second, the fact that you cited that seems to imply that the reason that people start drugs is usually because they are lacking respect and love. Why would you assume that a person starting drugs necessarily has any influence from other people's opinions of that person?