“Double down” comes from blackjack: you double your original bet, hoping your...

https://dlf-ne.org/is-up-the-ante-a-gambling-term-unpacking-a-classic-business-idiom/

“Double down” comes from blackjack: you double your original bet, hoping your next card seals the win. Learners often misuse it to mean just ‘try harder,’ but it’s about risk—doubling stakes when you sense advantage, not mere effort. Use it wisely.