“It’s immoral to let a sucker keep his money” (poker adage)

“It’s immoral to let a sucker keep his money” (or, “It’s morally wrong to let a sucker keep his money”) has been attributed to “Canada Bill” Jones (?-1880) in 1978, P. T. Barnum (1810-1891) in 1979, and W. C. Fields (1880-1946) in 2002. The gambling saying means that a professional sharp is obligated to take a sucker’s (amateur’s) money.
   
 
Wikipedia: Canada Bill Jones
William “Canada Bill” Jones (?-1880) was a noted confidence artist, riverboat gambler and card sharp. He has been described as “without doubt the greatest three-card-monte sharp ever to work the boats, perhaps the greatest of them all.”
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Quotations
“It’s immoral to let a sucker keep his money”
         
Google News Archive
19 July 1978, Toledo (OH) Blade, “More Famous Favorite Laws Come To Light” by Charles McCabe, pg. 17, col. 2:
Canada Bill Jones’ Motto: It is morally wrong to allow suckers to keep their money.
 
Google Books
7 September 1978, New Scientist, pg. 744, col. 1:
... and who is this thug Canada Billy Jones whose motto is that it is morally wrong to allow suckers to keep their money?
 
Google News Archive
1 November 1979, The Times-News (Hendersonville, NC), pg. 22, col. 2 classified ad:
Barnum’s Law:
It is morally wrong to allow suckers to keep their money.
(The Eudy Company—ed.)
 
14 March 1982, Seattle (WA) Daily Times, “Muddy memories: Racing season nears the starting gate” by Stanley Kramer, pg. A16, col. 2:
Well, I’ve learned. The gaming tables and the $2 windows think it’s morally wrong to let the suckers keep their money.
   
25 June 1982, Los Angeles (CA) Times, “Morning Briefing,” pg. SD B2:
Add Sleinbrenner: After being introduced as a man who “operates under the P. T. Barnum principle that says it is morally wrong to allow a sucker to keep any of his money,” Steinbrenner said, “Ownership of ports franchises is a big ego trip, and don’t let anybody tell you any differently.”
 
27 May 1984, Seattle (WA) Daily Times, “Contests: Barnum’s ‘sucker’ adage proven true once again” by Stanley Kramer, pg. A14, col. 6:
I’ve played Vegas often enough to know:
 
“You never let a sucker keep his money.”
   
The Internet Movie Database
Memorable quotes for
Rounders (1998)
Mike McDermott: It’s immoral to let a sucker keep his money.
 
Google Books
500 of the Most Witty, Acerbic & Erudite Things Ever Said About Money
By Philip Jenks
Petersfield, Hampshire: Harriman House Ltd.
2002
Pg. 34:
‘It is morally wrong to allow a sucker to keep his money.’
W. C Fields
     
The Herald (Scotland)
Monday 18 June 2007
The different brand of bung that exists in Spain . . . or does it?
Mark Wilson on Monday
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As WC Fields once put it, it’s morally wrong to allow a sucker to keep his money.