This confluence of events on the sports calendar also means an explosion of online betting. Unfortunately, Americans can also expect an increase in debt, bankruptcies, and losses of jobs and homes.

Predictably, gambling’s problems have also crossed over into the sports themselves, bringing the whiff of scandal and raising questions about the integrity of the games. Major League Baseball’s historic Opening Day game in Seoul was marred by news that Ippei Mizuhara, the interpreter for Shohei Ohtani, baseball’s biggest and highest-paid star, was fired by the Los Angeles Dodgers after running up millions of dollars in gambling debts, which were apparently covered with funds transferred from Mr. Ohtani’s bank account. Mr. Ohtani has denied ever placing bets or knowing about the interpreter’s use of funds from his private accounts, and MLB said it is investigating the incident.

Other sports have been touched by hints of scandals. The NBA said in March it was investigating Toronto Raptors star two-way player Jontay Porter over gambling irregularities. Some NBA players said they had received threats from gamblers after games. NCAA President Charlie Baker last month said he was asking states to ban bettors from wagering on student-athletes’ individual performances.

These problems stem from the 2018 Supreme Court decision Murphy v. NCAA, which struck down a federal ban on sports gambling and let the states set their own rules. Now 38 states and the District allow sports betting, spawning a proliferation of mobile betting apps and online sportsbooks — there are now more than 40 of them — representing a growing, multibillion-dollar industry. It’s also spawning a culture of addiction.

Americans last year bet $120 billion on sports. In January, sports betting revenue set a record monthly high of $1.48 billion, according to the American Gaming Association’s tracker. That comes as other forms of gambling — land-based in-person gaming such as at casinos, slot machines and gaming tables — declined.

Betting on sports competitions is at least as old as the ancient Greeks. But, in the modern iteration, mobile betting apps have made gambling easier than ever: You can place bets effortlessly with a few taps from the comfort of your living room.

Even more pernicious has been the rapid growth of in-game micro-wagers — known as “prop bets” — on specific aspects of any game in real time, which incentivize more spontaneous and impulsive gambling. How many free throws will a basketball player make in the first quarter? Who will hit the first home run of a baseball game? You can place a bet on that.

Add to that the now-ubiquitous, celebrity-studded advertisements for sportsbooks during games.

Big league sports once tried to keep a distance from gambling, fearing that betting might sully the games. Recall how Pete Rose, baseball’s all-time hit leader, was permanently banned from baseball for betting on baseball games, including his own team, the Cincinnati Reds, while he was a player-manager.

But after the Murphy decision, major league sports embraced gambling. Signing exclusive partnerships with the biggest sportsbooks, including FanDuel, DraftKings and Caesars — allowing use of their branding and trademarks for marketing — became a new way to keep fans engaged while creating a lucrative revenue stream.

Legalization did bring sports gambling into the open, where it can be regulated. But the gaming industry has resisted virtually all proposals for regulation. Cash-strapped states, addicted to the new revenue and always reluctant to raise taxes to pay for services, have hesitated to rein in a growing industry. Congress has also shown little appetite.

Some reasonable regulations should be imposed immediately. One bill in Congress would restrict ads during live games and prohibit use of “bonus bets” and other sweeteners. Attempts to restrict advertising will run into free speech concerns, but a model might be the restrictions legally placed on cigarette ads, premised on protecting public health.

That bill would also require sportsbooks to conduct “affordability verification” checks on their customers. Limits could be considered on the number of bets allowed in a single 24-hour period or the amounts of each bet.

A separate bill, introduced by Sen. Richard Blumenthal (D-Conn), would direct half the money from the current federal excise tax on gambling to addiction treatment and research. That deserves a hearing and a vote.

Sports and gambling are evermore intertwined. But there still might be time to put some sensible brakes on Americans’ dangerous, growing addiction to betting on sports.