The question is not "how many trillions should we spend on keeping someone alive" but "how much money should we spend on deliberately, actively killing someone"

The question is not "how many trillions should we spend on keeping someone alive" but "how much money should we spend on deliberately, actively killing someone", to which the answer is "zero". (I don't mean to downplay the fact that there are difficult questions for working out how much money a government should invest to add one quality-adjusted life-year to their citizens, or how to calculate QALYs in the first place, but governments do manage to do that and these questions are not the level that political controversies generally focus on. Also, I'm completely ignoring the issue of national defence here, as people can disagree on military posture based on other considerations).