From Longman Dictionary of Contemporary Englishgrow fat on somethinggrow fat on somethingRICHto become rich because of something – used to show disapproval The finance men had grown fat on managing other people’s money. → fat
Examples from the Corpus
grow fat on something• Magnus grew fat on brown wholemeal scraps and Gina gave up trying to keep him away.• The bull grew fat on his salary and expense account, but his performance was disappointing to say the least.• They could see themselves growing fat on large-scale construction payrolls.• These stock brokers grow fat on other people's money. 