During the war, there was a shortage of food which resulted in primitive methods of hunting and gathering but also in incorporating foreign food items into traditional dishes. Similar to today, the diet at that time mainly consisted of rice and kimchi. With the shortage, the Koreans collected discarded food items of the U.S. soldiers, added them to a common soup made from kimchi, and a delicacy was born. The discarded food items ranged from a can of beans, macaroni, and ham to cheese, bacon, and Spam. Any food with a U.S. army base origin could have been used for the soup.
Even with it's impoverished background, budae jjigae is commonly consumed today by all ages and classes. The stew can be found in many Korean restaurants in the U.S. Here in Southern Ca, where I reside, many restaurants in Los Angeles and Orange County serve it. In Korea there's even a "Budae Jjigae street" in Uijeongbu, which had a high concentration of army bases, that has a large number of restaurants specializing in the popular dish.
Although the soup is no longer made with discarded food items, the recipe still remains the same with the fusion of classic Korean ingredients with Western foods. The soup now typically consists of Spam, sausages, ramen noodles, etc. in a spicy stew that results in a unique flavor not commonly found in traditional Korean dishes. The stew is typically served family style over a burner at the meal table and is shared between multiple people. Growing up as a Korean American in the US, my fondest memories of eating budae jjigae was while socializing with friends over the Korean alcoholic beverage, soju, in a Korean cafe or restaurant or while camping with friends or family, enjoying the heat and spicyness in cold mountainous conditions.