Similar story with the Buran: they over-estimated the Space Shuttle's military capabilities on the assumption that the true intended mission profiles were being hushed up and ended up with a fully automated exoatmospheric nuclear bomber.
So it's a dodgy strategy if it's intentional: you've got to bet that your opponent will run out of cash before they can field the superweapons you've made them build; or that once built they won't be able to afford enough of them to make a difference.