Yes, because infrastructure, subsidies, education and social spending still need to happen and not paying your taxes will erode those things long before they stop a genocide. If you don’t care about getting in trouble with your government, there are more effective things that can be done.
That’s not something you can tell from the numbers given, because it depends on their total spending, not their losses. Maybe they spent 50B/year and made 40B/year back, leaving them with 10B in losses. I that case reducing the spending by 20% to 40B would make them even