“A race horse is an animal that can take several thousand people for a ride at the same time”

“A race horse is an animal that can take several thousand people for a ride at the same time” is a pun on the idiom “to take somebody for a ride,” meaning to cheat or deceive someone. A race horse has one rider, but can take many people for a ride—the gamblers who bet on a losing horse.
 
“A horse is the only animal that can take several thousand people for a ride at the same time” has been cited in print since at least April 1954, when it was printed in the syndicated “Little Liz” comic strip. The one-line saying has been included in several books of humorous quotations.
 
   
The Free Dictionary
take somebody for a ride
to cheat or deceive someone
 
30 April 1954, The Daily Mail (Hagerstown, MD),  “Little Liz” comic strip, pg. 4, col. 6:
A horse is the only animal that can take several thousand people for a ride at the same time.
 
Google News Archive
23 June 1960, Milwaukee (WI) Journal, Green Sheet, pg. 1 banner:
A Race Horse Can Take Several Thousand of Us People for a Ride at the Same Time
 
5 August 1960, Aberdeen (SD) American-News, “Today’s Chuckle,” pg. 3, col. 2:
A RACE horse is an animal that can take several thousand people for a ride at the same time.
 
Google News Archive
21 August 1960, Milwaukee (WI) Sentinel, pg. 1, right masthead:
TODAY’S CHUCKLE
A race horse is an animal that can take several thousand people for a ride at the same time.
 
Google Books
Speaker’s Encyclopedia of Humor:
Stories, Quotes, Definitions, and Toasts for Every Situation

By Jacob Morton Braude
Englewood Cliffs, NJ: Prentice-Hall
1963
Pg. 124:
Race horse: the only animal that can take several thousand people for a ride at the same time.
 
Google Books
14,000 Quips and Quotes for Speakers, Writers, Editors, Preachers, and Teachers
By E. C. McKenzie
Grand Rapids, MI: Baker Book House
1990, ©1980
Pg. 24:
A racehorse is an animal that can take several thousand people for a ride at the same time.
 
Google Books
20,000 Quips & Quotes
By Evan Esar
New York, NY: Barnes & Noble Books
1995, ©1968
Pg. 394:
A racehorse is the only creature that can take thousands of people for a ride at the same time.
 
Google Books
1001 Best Things Ever Said About Horses
By Steven D. Price
Guilford, CT: The Lyons Press
2006
Pg. 269:
A racehorse is an animal that can take several thousand people for a ride at the same time. —Source unknown
     
Google Books
The Little Red Book of Horse Wisdom
By Yvette Grant
New York, NY: Skyhorse Publishing
2012
Pg. ?:
A racehorse is an animal that can take several thousand people for a ride at the same time. —MARJORIE JOHNSON