While motives behind the Las Vegas massacre still​ remained very much in doubt, liberal pundits rushed out​ to blame the killer’s fascination with firearms for pushing an ordinary man to mass murder.

Actually, Stephen Paddock nursed another obsession far longer, and far more intensively, than he ever indulged an interest in guns—and that dangerous obsession has largely escaped condemnation in discussions of his horrifying crime.

For more than a decade, Paddock devoted most of his time and energy to compulsive gambling and—along with six million other American adults and a half-million teenagers—qualified as an obvious “problem gambler.” More than three quarters of those so afflicted suffer from clinical depression, and the problem impacts low income households far more commonly than it harms rich retirees like the Vegas killer.

Rather than encouraging gambling by promoting lotteries and casinos, government should try to limit damage from a devastating addiction that costs Americans $150 billion in annual losses.