After his discharge in 1970, Corapi studied accounting at Pace University and graduated in 1973. He joined an accounting firm in Las Vegas, Nevada, where he audited hotels and casinos. In 1975, he became assistant comptroller at the Tropicana Resort & Casino. A year later, he took a position with the Nevada Gaming Control Board as an investigator. He later operated his own bookkeeping firm for about a year before moving to Los Angeles, California in 1978, where he became a real estate agent.