“Double down” comes from blackjack, where you double your bet with a confident...

https://andersonssuperbthoughtss.timeforchangecounselling.com/wild-card-meaning-in-different-contexts-from-cards-to-corporate-boardrooms

“Double down” comes from blackjack, where you double your bet with a confident hand. In English, it means to commit fully, even if risk is high. Common learner slip? Saying “double up” instead—different meaning, don’t confuse the two. Keep your bets clear