The Canadian man sentenced last week for his role in a grandparent scam lived a lavish beachfront lifestyle, drove a Porsche and bought cocaine using money stolen from vulnerable seniors, according to the U.S. prosecutors who put him in prison.Sentencing documents filed in U.S. court say that Stefano Zanetti, 44, operated — or appeared to operate — a successful watersports rental company in Panama while he co-ordinated a multimillion-dollar fraud operation.“In reality, Zanetti was the lynchpin in an international conspiracy designed to systematically steal money from elderly victims in the United States,” Jeffrey R. Bengel, assistant U.S. attorney, wrote in…