“Double down” comes straight from blackjack: you double your bet when you’re...

https://dlf-ne.org/is-up-the-ante-a-gambling-term-unpacking-a-classic-business-idiom/

“Double down” comes straight from blackjack: you double your bet when you’re confident your hand will win. Language learners often misuse it thinking it means "do something twice," but it’s about increasing commitment, not repetition