“Double down” means to commit fully, like when blackjack players double their...

https://www.protopage.com/raymond-gonzalez4#Bookmarks

“Double down” means to commit fully, like when blackjack players double their bet after seeing their cards, betting on a win. Learners often confuse it with “double up,” but doubling down is riskier—you're raising the stakes, not just increasing numbers.