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

https://www.charliebookmarks.win/double-down-comes-from-blackjack-a-bold-move-where-you-double-your-bet-after

“Double down” comes from blackjack, where you double your bet after seeing your first two cards—riskier move, bigger potential win. Learners often think it means “do something twice,” but it’s about committing fully when stakes are clear