North Korea created a command economy built along Stalinist lines. When the Soviet Union collapsed imports of fuel, food and currency dried up. Without fuel the collective farms could no longer operate. Factories stopped working. Besides which there wasn’t much demand for North Korean goods anyway. Adverse weather created flooding and destroyed many of the existing crops. The Korean economy went into a nose dive. The system of food distribution collapsed and a black market and Darwinian capitalism surfaced.
In his book the Joys and Sorrows of Work author Alain de Bottom described how economies that instituted idealistic systems like socialism often collapsed whilst societies like Japan which focussed on producing computer games, plastic toys and gizmos flourished.