"Double down" started at the blackjack table—you're doubling your bet with just...

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

"Double down" started at the blackjack table—you're doubling your bet with just one more card, hoping for a lucky break. Learners often misuse it to mean "try harder," but it’s really about risking more when you already have skin in the game