The hip-hop mogul found it easy to set up his Roc Nation record label and build a musical empire because he already had years of experience illegally selling crack on the streets of Brooklyn in New York City, reported Vanity Fair magazine.
"I know about budgets. I was a drug dealer. To be in a drug deal, you need to know what you can spend, what you need to re-up," he said.
The 43-year-old now a reformed family man, wishes he had got out of the drug scene earlier and thought about the big picture instead of focusing on the instant cash.
"I was thinking about surviving. I was thinking about improving my situation. I was thinking about buying clothes."
Jay Z is married to Beyonce and raise daughter Blue Ivy with her.