to engage in risky behavior, especially when one is already in a dangerous situation.
This figurative usage as appearing in the Oxford English Dictionary is a meaningful explanation of “double down” other than the ubiquitous “to double the wager in exchange for only one additional card in Blackjack gambit” in every online dictionary.
Don’t try to double down the exposures of your retirement money in aggressive investments
It is the time to double down on the commitment of solar energy, rather than to scale back
HP is going to double down on Palm’s webOS