“Double down” comes straight from blackjack: when you’re confident, you double...

https://telegra.ph/Why-Do-Native-Speakers-Not-Notice-Idiom-Origins-07-29

“Double down” comes straight from blackjack: when you’re confident, you double your bet and hope for a good card. Learners often mess this up, thinking it means just “try harder” in any situation. Nope—it’s about backing your bet, not vague effort