To Sam DeMello’s friends, it seemed as if the then-26-year-old had everything together: a six-figure tech salary, an enviable workout regimen and a happy relationship. But as he crossed the finish line of the 2013 Nike San Francisco marathon, he was surrounded by a deep sense of self-loathing.

His friends, family and girlfriend had no idea he was struggling with a crippling sports betting addiction. He fell into it just a few weeks after being introduced to sports gambling, though he didn’t realize it until years later.

“All of my friends would come to me and say: 'Congratulations, man, you're crushing it. We're so proud of you,’” DeMello says. “I would just feel this dissonance, because I felt so fraudulent.”

DeMello, now 38 and in recovery, wishes he saw the warning signals sooner.

As legalized sports betting grows across the United States, a growing number of young men are falling into gambling addictions without recognizing the signs. Driven by the explosion of mobile betting platforms and a lack of age-targeted resources, many see betting as a form of entertainment or investing − until it’s too late.