“Double down” comes from blackjack: you double your bet when confident in your...

https://kylersultimatethoughts.wpsuo.com/why-idioms-do-not-belong-in-legal-documents

“Double down” comes from blackjack: you double your bet when confident in your hand, doubling risk and reward. Learners often think it means simply “try harder,” but it’s about upping the stakes, not just effort