It’s also caused problems: Those treating compulsive gambling say calls to their hotlines seeking help have increased significantly in the five years since sports betting was legalized and made available on cell phones. Legalization of sports betting has opened up opportunities: additional tax revenue for states, a small auxiliary revenue stream for casinos and horse tracks, and a way to keep many people away from the dangers of unregulated offshore gambling web sites. Betting odds are now an integral part of broadcasts of many games. Since then, some once-unthinkable changes have happened: Professional sports leagues, which fought New Jersey tooth and nail right up to the Supreme Court in an ultimately unsuccessful effort to prevent legal betting, now partner with gambling companies, slather their ballparks with sports betting advertising and some even have betting outlets in their stadiums.