Coincidental Irony, or Commercial Stereotype?

I think his substance abusive past and recovery may just be something that gives him an edge over other actors when it comes to playing these characters. Having these experiences first hand, he can bring something extra to that type of role that another actor may not be able to and I'm sure that is something directors realize (as well as Downey himself). Downey ultimately has to say yes to playing these type of parts. He may as well capitalize on his real life experiences, which it seems, is exactly what he is doing.