“Double down” means to commit fully to a risky choice, from blackjack where you...

https://idiominsider.com/talking-odds-at-work-the-risk-idioms-every-english-learner-gets-slightly-wrong/

“Double down” means to commit fully to a risky choice, from blackjack where you double your bet for one last card. Learners often think it’s about hesitation or withdrawing—actually, it’s doubling effort, not backing off