"Double down" comes from blackjack—when you double your bet after seeing your...

https://zandersnewop-ed.lucialpiazzale.com/what-does-double-down-mean-in-business-meetings

"Double down" comes from blackjack—when you double your bet after seeing your first two cards, betting you’re onto a winner. Language learners often overuse it, thinking it means just 'try harder.' Nope, it’s about risk, not effort