make out like a bandit

Succeed extremely well, as in He invested in real estate and made out like a bandit. This expression likens other forms of success to that of a triumphant robber. It may, however, come from an intermediate source, that is, the use of bandit (or one-armed bandit) for a slot machine, which is far more profitable for the house than for gamblers. [Slang; c. 1970]