Lost, or invested? One imagines if they outright lost it and saw no opportunity to recoup (i.e. no longer an investment) they'd just end the program.
Boeing wouldn't need to pay anything.
People say that, but I don't think it's true. Boeing pulled out of the Phantom Express project seemingly unscathed.
https://www.space.com/boeing-withdraws-darpa-military-space-...
Pretty sure SpaceX is cheaper, so NASA will be the only customer.