“Double down” comes straight from blackjack—the gambler doubles their bet when...

https://www.slideserve.com/katherine_turner08/free-spins-and-scatter-symbols-explained-gambling-origins-meet-everyday-english

“Double down” comes straight from blackjack—the gambler doubles their bet when feeling confident, aiming to double the win. Learners often misuse it to mean “redo” or “try again,” but it’s about committing more when the odds look good, not starting over