People want internet gambling, and the NCAA basketball tournament drives billions of illegal gambling dollars. But a Wisconsin man is trying to combat gambling addiction before it’s too late. “Don’t gamble,” said Robert McGuigan, a simply message he’s been preaching since 2006. “I had no idea gambling was even an addiction.” McGuigan’s son, Jason, was a known gambler. He was murdered inside his Verona home in 2003. The killer, Mark Wu, was upset he didn’t win $17,000 on a bet Jason never placed for him. Three years later, Robert turned his agony into action. “It was like a light bulb…