Kurt Freudenberg was 11 when he started gambling. By college he was betting 15 hours a day — an addiction that led him to seek treatment.

Despite rules or bans in most states, underage gambling has become the newest vice tempting America's youth. The explosion of online sportsbooks like FanDuel and DraftKings has made it easier than ever for kids to place wagers — often without parental permission, leading to dangerous consequences.