Phil Mickelson reportedly bet over $1 billion on sports, with losses of around $100 million, according to a book by Billy Walters.

Mickelson allegedly attempted to place a $400,000 wager on Team USA during the 2012 Ryder Cup.

Billy Walters, a successful bettor, scolded Mickelson for considering the Ryder Cup bet, citing risks to his reputation.

Mickelson denied ever betting on the Ryder Cup and emphasized his commitment to maintaining the game's integrity.

Mickelson's history of sports gambling includes links to money laundering and an alleged mob bookie, though he was not charged.

In 2022, Mickelson admitted his gambling addiction had become "reckless" and "embarrassing."

Walters and Mickelson formed a betting partnership in 2008, giving Walters access to Mickelson's offshore sportsbook accounts.

The partnership ended in 2014 amid federal investigations into stock trades made by both Walters and Mickelson.

Walters was convicted of conspiracy, securities fraud, and wire fraud, with his sentence later commuted by President Trump.

Walters expressed disappointment that Mickelson didn't testify on his behalf during the legal proceedings