>>17922237 (OP)
Soviet economics is a failure. If you meant 'What killed the Soviet economy' then it was Soviet economics - which is so bad that people were starving while they had more than enough of the most fertile land on Earth to feed everybody in the USSR, and they went broke while owning the largest single share of the worlds resources.
Communist theory and praxis are just that fucking retarded. If you were trying to intentionally ruin a country your plan would look almost identical to Communist orthodoxy.