make out like a bandit - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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]