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

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

“Double down” jumps from blackjack, where you double your bet after seeing your first two cards, betting on a winning hand. Learners often misuse it to mean “do twice as much” generally, but it’s specifically about risking more when odds look good