Hotteok is a doughnut with the sugar on the inside. The 60g of dough is 150 calories, the 25g of brown sugar and cinnamon filling melts into about 90 calories of syrup, and the griddle is slick with oil, so each piece picks up 5g or so, another 45. That is 280 in something you finish in 4 bites while walking.
The seed hotteok (씨앗호떡) from Busan is not the healthy version, even though it has sunflower seeds and nuts in it. Fatsecret.kr lists it at 363 per piece, higher than plain, because it is deep fried in a shallow pool of oil rather than griddled, then split and stuffed with seeds and more sugar.
The price makes it dangerous. At 1,500 won a piece, two hotteok is 560 calories for 3,000 won, which is the same as a full bowl of bibimbap for a quarter of the cost. Winter markets in Seoul usually have a hotteok cart within 30 metres of the bungeoppang cart, and people hit both.