You know he has a drinking problem, or you suspect it based on his behavior?
The latter. Bearing in mind Alcoholism has a diagnosis -- and symptoms, including grandiosity.
And doesn't give a damn who you are and/or what you do for a living -- and afflicts equal percentages of kings, queens, princes, princeses presidents, corporate heads, judges, accountants, wharf laborers janitors, laborers, bums, layabouts, lawyers and actors.
Also, if you sniff him out on Lexis Nexis you'll find a lot of references to his "ecentricity" and the like.