Dustin Johnson says it is an "unbelievably difficult" decision to withdraw from the Masters and the worst part is he feels like he'll be fine in two days. (1:01)

Johnson: 'I'm not going to be able to compete like this' (1:01)

Dustin Johnson walked to the first tee at Augusta National on Thursday. The fact that he pulled out of the Masters without ever teeing off resulted in some gamblers getting their money back and others losing it either way.

Among the Las Vegas sportsbooks refunding money -- taking the belief that the bet is off if the golfer doesn't play -- are Westgate, South Point, Wynn, Golden Nugget and Station Casinos.

Others, including MGM, Boyd Gaming, Caesars, CG Tech and William Hill (the largest Nevada sportsbook operator in terms of number of sportsbooks and market share), told bettors that Johnson's lack of a single stroke in the year's first major championship still results in a lost futures bet.

More money was bet on Johnson to win this year's Masters than any other golfer at multiple Las Vegas sportsbooks.

"It has always been the case for us," spokesman Michael Grodsky of William Hill, which operates 108 sportsbooks in the state, said of its policy. "We had it for years when Tiger [Woods] didn't wind up playing, and it's not only golf. When Ole Miss got their bowl ban [in February], that didn't mean that anyone who bet on Mississippi got their money back."

Grodsky said those who bet on Johnson on a prop or a matchup would get their money back.

But the future bets are where the big money is wagered, and there's no controversy as far as those books are concerned. Future bet wagers note that "all bets are action" regardless of whether a golfer plays.

Grodsky said Johnson, Rory McIlroy and Jason Day each garnered 7 percent of his sportsbook's future bets on the Masters. Only Jordan Spieth had more (11 percent).

"It's the risk you take," MGM assistant sportsbook manager Jeff Stonebeck said. "If it's a weekly tournament, it's more likely that a sportsbook will return a bettor's money."

For some, it's a customer service issue.

The Race & Sports Book at Wynn is giving back money to people who bet on Johnson. It does not, however, give back money to those who bet on Kentucky Derby horses if they don't race.

"Under normal circumstances, we wouldn't give back the money, but for the last couple years, for the majors, we've decided to give back the money if a golfer doesn't tee off," said Johnny Avello, who runs that book. "It turns out to be such a hassle not to do the refund because for the next three months all you hear from those customers is about the money they lost."

Because of the intense competition for bettors' money, many of the online sportsbooks require a golfer to actually tee off for it to be considered action. That's why anyone who bet on Johnson on sites like Pinnacle and Bovada is getting money returned.

For many Las Vegas sportsbooks, the feeling is that money can't be returned after so much time invested in taking bets.

"For us, when a top guy doesn't play, it has a huge impact on the odds of the other players," Boyd Gaming's Bob Scucci said. "We're putting up futures months and months in advance."

When news broke of Johnson's fall Wednesday, the world No. 1 went from being the consensus favorite to falling below Spieth and McIlroy when those players teed off Thursday.

Johnson pulled out of the tournament shortly before teeing off Thursday afternoon, after falling down a staircase and injuring his back at his rental home a day before.