If you ever wondered what it would be like to retire as a multi-millionaire at age 28, you might want to take a look at Michael Phelps.

Remember him? The most decorated Olympian in history has decided to call it quits, and now he's got all the time (and money) in the world.

Playing in tons of golf tournaments? Check. Diving with sharks off the coast of South Africa? Check. Casually dropping $5,000 to enter the most prestigious poker event in the world? As of this week, check.

Phelps was in Las Vegas this week, and since he's got several professional poker-playing friends, he decided to head over to the tables. And before long, he was buying in and sitting down.

"It’s kind of weird," Phelps told Card Player. "I wasn’t even going to play today. I just wanted to come over and see everything and somehow these guys talked me into playing. Antonio (Esfandiari) and JG (Jeff Gross) told me we should just throw in a buy-in and see what happens at your first World Series event."

Phelps is far from a newcomer to poker tournaments. He played admirably a few months ago in the Bahamas and he's even made the final table at a high-stakes event.

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