"Double down" comes straight from blackjack—when you’re so sure of your hand...

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

"Double down" comes straight from blackjack—when you’re so sure of your hand you double your bet and take one more card. Learners often mix it up, thinking it means playing it safe. Nope. It means committing fully, doubling your stakes, risks and all