LAS VEGAS — Floyd Mayweather is about to close in on $1 billion in career fight earnings after his bout with Conor McGregor on Saturday at T-Mobile Arena. The vast majority of that haul has come since 2006, when Mayweather made a $750,000 bet on himself.

Back in 2006, Mayweather declined an $8 million offer from his promoter, Top Rank, to fight Antonio Margarito. He chafed at what he saw as Top Rank’s favoritism toward Oscar De La Hoya, then the No. 1 attraction in the sport, and publicly bickered with Top Rank chairman Bob Arum over the way Arum chose to promote him.

[Related: No shortage of Mayweather-McGregor prop bets]

So rather than accept the $8 million for a fight he probably would have won easily, Mayweather paid Top Rank $750,000 to get out of his contract and promote himself or, in his parlance, be his own boss.

It was a massive risk because it seemed to end any hope for a fight with De La Hoya, and most financial advisers would say it is better to earn $8 million than to spend $750,000.

A little over a decade later, though, Mayweather continues to cash in on that so-called risky bet.

Mayweather was great in the ring from his earliest days as a pro, but in the first 10 years of his career, “Pretty Boy” Floyd struggled to sell tickets and gain public acceptance.

An announced crowd of 5,123 showed up at the MGM Grand on March 18, 2000, to watch him take on Gregorio Vargas in what was his fifth defense of his WBC super featherweight title. The Los Angeles Times reported in its March 19, 2000, edition (without noting a source) that 1,500 of the tickets were complimentary.

In that same story, the Times reported Mayweather had declined a reported six-fight, $12.75 million contract extension offered by HBO.

A few months earlier, when talks of an extension were just beginning, then-HBO Sports president Seth Abraham proposed a four-fight, $5 million extension.

Mayweather told Abraham he’d one day become the first boxer to earn $100 million in a single night. He instantly sloughed off Abraham’s offer during a meeting in Abraham’s New York office as “slave wages.”

“The meeting started to get pretty heated and I sent everyone out of the room but Floyd and myself,” Abraham told Yahoo Sports. “I said to him, ‘Floyd, we have been paying you hundreds of thousands of dollars and now we’re offering to pay you millions of dollars. You have to explain to me how you can possibly turn that down.’ He said, ‘Seth, those are slave wages.’ I responded by saying, ‘Floyd, if those are slave wages, you’re going to have to show me the way to that plantation.’ ”

As the final seconds wound down in the Vargas bout, HBO Sports play-by-play man Jim Lampley referred to the bout “a test of [Mayweather’s] overall professionalism and a chance to show off all of his varied skills against a guy who knows how to fight.”

In response, ringside analyst Larry Merchant, one of the sport’s most astute observers, added, “Having said that, he doesn’t look like any $12 million fighter to me.”

That was the perception of boxing insiders at the time, that Mayweather’s view of his worth and reality were 180 degrees opposed.

And so, even after beating Vargas by a unanimous decision, Mayweather didn’t land the long-term HBO deal. An agreement was made with then-IBF 130-pound champion Diego Corrales to fight Mayweather and the winner would get the HBO deal.

Mayweather won the fight, scoring five knockdowns, stopping Corrales in the 10th and landed the lucrative TV deal.

The HBO deal doubled Mayweather’s per-fight paycheck, from an average of $1.25 million to $2.62 million. But Mayweather wasn’t satisfied.

He wanted to box De La Hoya, had since 1997 when he was just six months into his professional career. Fighting on the undercard of De La Hoya-Pernell Whitaker, in what was billed as a fight for pound-for-pound supremacy, Mayweather was asked after beating Bobby Giepert who he wanted to fight next.

“The winner,” he responded, choosing not to call out someone at his level.

He believed less than a year into his pro career that he was good enough to compete with, and defeat, the best.

“The great thing about boxing is when the best fight the best,” Mayweather told Yahoo Sports. “That’s all I ever wanted, was to be able to fight the best.”

De La Hoya was, along with heavyweight Mike Tyson, the biggest star in the sport at the time. He was getting the attention and the promotion from Top Rank that Mayweather craved.

No matter how good of a job Top Rank did in promoting him, Mayweather wasn’t satisfied. He wanted to be portrayed differently and promoted to a more urban market.

He also wanted to fight De La Hoya. When Top Rank didn’t come through with those two things, Mayweather made the decision to buy his way out of his deal.

“He kept asking us to market and promote him to that hip-hop market and he turned out to be 100-percent correct,” Top Rank chairman Bob Arum told Yahoo Sports in 2015. “He left us and he went out and did that and he became hugely successful with that market.”

He made $8 million to fight Carlos Baldomir on Nov. 4, 2006, then finally landed the fight he’d always wanted. He not only got the De La Hoya fight, he made $25 million, $5 million more than what Top Rank and Arum had earlier scoffed at as exorbitant.

“Pretty Boy” ceded to “Money” Mayweather. McGregor will be Mayweather’s 15th fight since breaking free of Top Rank. In that time, he’s sold more pay-per-views and generated more pay-per-view revenue than any other fighter. He has the three biggest gates in Nevada history and five of the top six. And if Saturday’s bout goes the distance, Mayweather stands to earn roughly $7.22 million per minute … or just a little less than Top Rank would have paid him for fighting Margarito a little over a decade ago.

“I think a critical turning point in Floyd’s career was buying himself out of the Top Rank contract,” said Stephen Espinoza, the executive vice president and general manager of Showtime Sports. “That is going out on a limb, paying $750,000 with no guarantees on what’s going to happen on the other side of that. Without the courage to make that move, without the foresight to make that move, none of the rest of this is possible.

“It’s easy to sit back and forget that it all starts with taking risk. No one has this level of success without taking a risk, and that’s one very tangible point where Floyd put his money where his mouth is, took the risk and was able to reap the rewards.”

That includes a $260 million payday against Manny Pacquiao in 2015 and a similar haul Saturday night in what is expected to be the largest grossing fight in boxing history.

UFC president Dana White said it is “very realistic” for the bout to reach five million on pay-per-view.

“Pre-buys are off the charts and way more than Mayweather versus Pacquiao,” White told Yahoo Sports. “UFC.TV pre-buys are 47 percent first-time customers. The only pre-buys I don’t have yet is DirecTV, [but] all the other systems are crushing Mayweather-Pacquiao on pre-buys. This is by far the biggest [financial] fight ever.”

And that likely doesn’t happen if Floyd Mayweather doesn’t make a $750,000 bet on himself a little more than a decade ago.

More Mayweather-McGregor coverage from Yahoo Sports:
• Mayweather goes ‘insane’ over Bieber social media act
• What happens if McGregor beats Mayweather?
• How Ali’s ugliest fight paved the way for Mayweather-McGregor