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

https://sierra-wiki.win/index.php/Hedge_Your_Bets_Meaning:_Finance_vs_Everyday

“Double down” comes from blackjack, where you double your bet after seeing your first two cards, betting on a strong hand. Learners often misuse it to mean simply ‘try harder,’ but it’s about committing more resources despite risk