“Double down” comes from blackjack, where you double your bet after seeing your...
https://utopian-bunny-9c7.notion.site/Double-down-comes-straight-from-blackjack-you-double-your-bet-when-you-re-3ac32fcbb5b980c99bb6d0c3a6d73011
“Double down” comes from blackjack, where you double your bet after seeing your first cards, hoping to beat the dealer. It means taking a bigger risk to win big. Learners often say “double up” instead—a close miss, but it means something else entirely.