Robert Downey Jr, or How to play an Alcoholic

Is it me or is Robbie-D monopolizing all the high-profile "alcoholic" characters in Hollywood?
[No complaints of course... just saying]

Example Numero Uno:

Paul Avery in David Fincher's Zodiac
Example Numéro Deux:

Principal Gardner in Charlie Bartlett
and of course Example Number Three:

Tony Stark in Jon Favreau's Iron Man