This article is part of TPM Cafe, TPM’s home for opinion and news analysis. It was originally published at Balls and Strikes.

In 2017, Americans legally wagered $4.9 billion on sporting events. Last year, they bet over $165 billion. And the true costs of their bets were even higher: One-quarter of sports bettors, surveyed by U.S. News last summer, worried that they couldn’t control their gambling. Over 30,000 people reach out to the National Problem Gambling Helpline every month.

“Problem gambling,” a term referring to an inability to control gambling behavior that results in personal or financial harm, is at least twice as common among sports bettors as among gamblers in general. It’s unsurprising, then, that Congress enacted a law decades ago that prohibited sports gambling throughout much of the country. But in 2018, the Supreme Court struck that law down, freeing states to partner with the gambling industry to profit off their vulnerable residents. A growing body of research shows Americans are now paying the price.