“Cocaine is God’s way of saying you have too much money” was said by American actor and comedian Robin Williams following the drug-overdose death of his friend, comic actor John Belushi (1949-1982). The quote was recorded in a newspaper published on August 3, 1982.
 
There have been several variations on the quotation, such as “Weed is God’s way of saying you have too much money.”
   

Wikipedia: Robin Williams
Robin McLaurin Williams (born July 21, 1951) is an American actor, voice actor, and stand-up comedian. Rising to fame with his role as the alien Mork in the TV series Mork & Mindy, Williams went on to establish a successful career in both stand-up comedy and feature film acting. His film career includes such acclaimed films as Good Morning, Vietnam (1987), Dead Poets Society (1989), Awakenings (1990), The Fisher King (1991), and Good Will Hunting (1997), as well as financial successes such as Popeye (1980), Hook (1991), Aladdin (1992), Mrs. Doubtfire (1993), Jumanji (1995), The Birdcage (1996), Night at the Museum (2006), and Happy Feet (2006).

Nominated for the Academy Award for Best Actor three times, Williams went on to receive the Academy Award for Best Supporting Actor for his performance in Good Will Hunting (1997). He has also received two Emmy Awards, four Golden Globes, two Screen Actors Guild Awards and five Grammy Awards.
   
Google News Archive
3 August 1982, Miami (FL) News, pg. 1A, col. 1:
Quote Unquote
‎Robin (Mork) Williams discussing the death of his friend, John Belushi: “Cocaine is God’s way of saying you have too much money.”
   
Google Books
The Jekyll & Hyde Syndrome:
A New Encounter with the Seven Deadly Sins and Seven Lively Virtues
By H. Stephen Shoemaker
Nashville, TN: Broadman Press
1987
Pg. 74:
The comedian Robin Williams said it well: “Cocaine is God’s way of saying, ‘You have too much money.’”
 
Google Books
I am a VCR:
A book by TV’s number 1 critic about sex & violence, Dynasty & Dallas, T & A, N.Y. & L.A., drugs, Roone Arledge & hero cars
By Marvin Kitman
New York, NY: Random House
1988
Pg. 266:
“It’s the movie people who do drugs,” Ross said. “TV writers can’t afford it. Coke was put on earth by show-business people to show that you are important. Cocaine is God’s way of saying you have too much money.”
     
Democratic Underground
NNadir
Wed Feb-01-06 05:02 PM
10. Cocaine is nature’s way of saying you have too much money and deserve none
of it.
   
Google Books
HowDunit—The Book of Poisons
By Serita Stevens and Anne Bannon
Cincinnati, OH: Writer’s Digest Books
2007
Pg. 252:
Once known as God’s way of saying you have too much money, because it was so expensive, cocaine use has grown and spread throughout much of the economic spectrum.