Idioms and Phrases with ill-gotten gains
Benefits obtained in an evil manner or by dishonest means, as in They duped their senile uncle into leaving them a fortune and are now enjoying their ill-gotten gains. [Mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.