A vampire riddle has been cited in print since at least 1999:

Q: What do vampires play poker for?
A: High stakes.

A slightly different version—not necessarily involving the game of poker—was posted on Twitter on December 1, 2013:

Q: Why are vampires afraid of casinos?
A: Because of all the high stakes.

This version involving slots was posted on Reddit—3amjokes on April 25, 2018:

“You can only find a vampire playing penny slots at the casino. They hate games with high stakes.”

“Why don’t vampires gamble?"/"They can’t deal with those stakes” and “Why don’t vampires play poker?"/"They are afraid of the stakes” are related riddles.


Google Books
The Silly Little Book of Monster Jokes
Bath, UK: Parragon Book Service Limited
1999, 2001.
Pg. ?:
What do vampires play poker for?
High stakes.

Google Books
Extreme Monsters Joke Book
By Nikki Bataille Lange, Randy Meredith and Eric Smith
Columbus, OH: Penny Candy Press
2005
Pg. 28:
What do vampires play poker for?
High stakes!

OCLC WorldCat record
High stakes / A Tale of Vegas Vampires
Author: Erin McCarthy
Publisher: New York : Berkley Sensation, 2006.
Edition/Format: Print book : Fiction : English : 1st ed
Summary:
From the “USA Today” bestselling author of “A Date with the Other Side” comes a vampire-meets-girl story set in the city that never sleeps--except during daylight.

Google Groups: Palace of Adult Humor
Vampire Jokes
Dangermo...@aol.com
10/31/06
(...)
What do vampires play poker for ?
High stakes

Twitter
Monica Beckett
@moniemouse
What do vampires play poker for?High stakes...Can’t wait until tomorrow night! TRUE BLOOD ~_~
7:50 PM - 27 Jun 2009

Twitter
DealerDolls.com
@DealerDolls
What do vampires play poker for?
High stakes.
1:53 PM - 25 Oct 2009

Twitter
⚯͛ shaunna. △⃒⃘
@TheRipperxo
“When vampires go to the casino they play high stakes.” - Tony, the only thing he’s ever said that makes sense hahaha.
4:31 PM - 16 Dec 2011

Twitter
Casino Hire London
@Casino4London
Christmas Casino Cracker Joke #1 What do vampires play Texas Hold ‘Em for? High stakes!
4:46 AM - 8 Nov 2013

Twitter
Lucifer Ordog
@DeepDarkFear
Why are vampires afraid of casinos?
Because of all the high stakes.
1:43 PM - 1 Dec 2013

Google Books
Insults Anywhere Kids Presents
Joke Book Of The Living Dead
By Franklin Yantz
Insults Anywhere
2014
Pg. ?:
What do vampires play poker for ?
High stakes !

Twitter
Free Poker Games
@Free_Poker_Game
What do Vampires play poker for?...........High Stakes. BOOM BOOM!! #casino
11:16 AM - 27 Mar 2015

Twitter
Ludious
@LudiousTSW
Where is the vampire casino I want to make high stakes puns forever
9:05 AM - 18 Jul 2015

Twitter
Redbet Live
@RedbetLive
Q: What do Vampires play poker for?
A: High Stakes!
#Poker #Joker
2:30 AM - 28 Feb 2018

Reddit—3amjokes
You can only find a vampire playing penny slots at the casino self.3amjokes
Submitted April 25, 2018 by seannywanny
They hate games with high stakes