Hot Millions (1968) on Netflix

Marcus is just out of prison for embezelment but discovers that it is no longer a world of ledgers but has become one of computers. Looking for an angle, he convinces Caesar Smith, noted computer whiz to follow his life long desire, to hunt butterflies in the Amazon. Using Caesar's resume, he finds employment in the corporate world and begins a very large operation under the noses of his superiors. On this journey, he meets Patty, who seems to have no real tallents at all. Marcus marries her, as Ceasar and now has the problem of hiding his hot cash.