“Double down” comes from blackjack, where you double your bet after seeing your...

https://www.echobookmarks.win/double-down-comes-straight-from-blackjack-you-re-doubling-your-bet-when-the

“Double down” comes from blackjack, where you double your bet after seeing your first two cards, banking on a strong hand. Learners often confuse it with “double up,” but doubling down means taking a bigger risk to win big, not just increasing something