I think being able to walk away from a project like this is actually quite commendable, in a way. Not that it's always the right call, but to be able to avoid the 'sunk cost fallacy'[1] on this scale is something that large governments/companies seem rarely capable of. That said, in this case, maybe they just didn't have a choice and ran out of money... [1] https://en.wikipedia.org/wiki/Escalation_of_commitment
Robert Gates killed a couple of large-budget defense projects while Secretary of Defense. The airborne laser which had "16 years of development and a cost of over $5 billion"[1] was cancelled in 2010 under his watch. Quoting from Wikipedia, sorry: [1] https://en.wikipedia.org/wiki/Boeing_YAL-1
"If the ABL had achieved its design goals, it could have destroyed liquid-fueled ICBMs up to 600 km away. Tougher solid-fueled ICBM destruction range would likely have been limited to 300 km, too short to be useful in many scenarios, according to a 2003 report by the American Physical Society on National Missile Defense."