Bill Bradley, the basketball Hall of Famer and former United States senator known as a staunch opponent of legalized sports betting, was speaking about the topic back in January. But he might as well have been predicting the future.

“Well there hasn’t been a scandal, yet,” he said, discussing how professional sports have become ever more entwined with the gambling industry in recent years. “So the worst has been avoided, but all of the conditions are there for the untoward to occur.”

On Wednesday, the National Basketball Association confirmed the untoward had occurred, issuing a lifetime ban to Jontay Porter, a seldom-used backup forward for the Toronto Raptors. The league said Mr. Porter wagered money on his own team to lose, pretended to be hurt for betting purposes and shared confidential information with gamblers.

“There is nothing more important than protecting the integrity of N.B.A. competition for our fans, our teams and everyone associated with our sport,” Adam Silver, the league’s commissioner, said in announcing Porter’s punishment.

There are those who worry that Porter is just the tip of the iceberg across American sports, and that unless everyone — leagues, players, unions, politicians, betting companies — gets together to prevent further betting scandals, the very viability of professional sports is at risk. The Porter case was all the more unsettling because it came just weeks after baseball’s biggest star, Shohei Ohtani, was connected to a gambling scandal when his longtime interpreter was accused of stealing millions of dollars from him to pay an illegal bookmaker.

“When sports lose the perception that they’re honest, their sport dies,” said Fay Vincent, the former Major League Baseball commissioner who played a key role in barring Pete Rose, the career hits leader, from the sport for life in the 1980s because he bet on his own team’s games.

Sports leagues and gambling companies argue that betting will take place whether or not the law allows it, so legalizing and regulating it protects the games by making it much easier to identify suspicious wagers. (Gambling on sports is now legal in 38 states.) That is what the N.B.A. said happened with Porter. Suspicious wagers on a game involving Porter were brought to the N.B.A.’s attention, according to the league, “by licensed sports betting operators and an organization that monitors legal betting markets.” A few weeks later he was gone from the sport.

Porter’s agent did not respond to a request for comment.

However, if not for the significant size of the bet, it is not clear that any actions by Porter would have been detected.

About 15 people in the N.B.A.’s offices and four or five lawyers are involved in the league’s efforts to educate players about its gambling policies, and to monitor and enforce those policies. The league has relationships with private organizations that monitor gambling, such as U.S. Integrity and Sportradar, as well as state gambling regulators and betting operators, all of whom can alert the league to suspicious activity that might involve players or other league or team personnel.

The N.B.A.’s investigation found that somebody associated with Porter bet $80,000 that, essentially, he would perform poorly in a game on March 20. These kind of wagers, known as prop bets, are not directly related to the outcome of the game. Instead they are wagers on specific in-game possibilities, like whether a player will score a certain number of points. Prop bets are often combined into a single wager called a parlay. Such bets have extremely low odds, but give high payoffs if successful.

Against the Sacramento Kings on March 20, Porter played just three minutes before leaving with what the team said was an illness. The $80,000 bet on his performance by his associate would have resulted in a $1.1 million payout if the suspicious activity hadn’t been detected, the league said.

There are few sportsbooks in the country that would even take an $80,000 bet on a prop parlay, let alone one involving a player like Porter.

The N.B.A. said its investigation also found that, from January through March, Porter placed “at least 13 bets on N.B.A. games using an associate’s online betting account.” Three of the bets were multigame parlays that involved Raptors games — he did not play in any of those games — and all were bets that the Raptors would lose.

Porter was a marginal player in the N.B.A., not necessarily the type who could be guaranteed to affect whether his team won or lost. But the individualized nature of many prop bets means more players are able to have a more direct impact on whether a wager is successful. The president of the N.C.A.A. has said that he would like to ban prop bets involving college athletes.

Mr. Vincent said he was not particularly confident that the current legal apparatus around sports gambling — consisting of different league regulations and varied state laws — combined with a public mostly excited to pull out their phones and bet $10 on a game, was an effective system to prevent or catch all problematic wagers. The N.B.A., like most professional leagues, has pushed for a federal law that would regulate all sports gambling in the United States, though that does not seem likely in the near term.

“I’m 85 years old so I won’t be around, but I don’t think the next 20 or 30 years is going to be a pretty story about gambling in the sports world because the money is going to be so enormous, and wherever the money is enormous the corruption follows,” he said.

The N.B.A. spends a lot of time educating its players on the rules around betting, especially the prohibition against wagering on basketball. The league does not allow the gambling companies it partners with to offer bets on its development league, the G-League, because it does not want to open up the possibility of players making less money than those in the N.B.A. being tempted to wager on their own sport. Last year, players in the National Football League and the National Hockey League were suspended for violating betting rules.

And yet Porter, who received these trainings and earned around $2.7 million in his N.B.A. career, which began in 2019 — and whose brother, Denver Nuggets wing Michael Porter Jr., will earn $33 million this season — still risked banishment.

Jontay Porter posted often on social media about trading stock options and cryptocurrencies, and co-founded a company to teach others to do the same. Devin Mills, a professor in Texas Tech University’s Department of Community, Family and Addiction Sciences, said it was not uncommon to see those interests overlapping with sports betting.

Mills said sports betting, similar to trading stock options and cryptocurrencies, was associated “with this kind of this characteristic where individuals study and really think they can beat the system because they know the game, they know the players, and there is some sort of trend analysis.”

Trading options, speculating on cryptocurrencies and betting on sports are all activities that can now be accomplished with a few clicks on a smartphone. They have all exploded in popularity in the last few years, especially with younger men who spend a lot of time online.

It is the crux of the problem for professional sports leagues, which encourage their fans to bet at the same time that they warn their players away from it.

“Do we have to help them identify an alternative activity to stimulate their mind and emotions, so they aren’t seeking the rush through betting?” Mills said.

Jenny Vrentas contributed reporting.