Why learn makeup in Busan if the Korea trip in my head feels bigger than one city?
Because the feeling you came for is the skill, not the city printed on the receipt. Everyday Korean makeup, taught on your face, in English, is the part of the trip you still use at home. Doing it on a day you are already in Busan is how the trip stays on you after you leave.
The skill, not the city on the receipt
The answer separates the feeling you came to Korea for from the city name on a booking. Everyday Korean makeup, taught on your face, in English, is the part you still use at home. Busan is where the hour happens to be available on this trip. The skill does not stay behind in the city.
Why “while you are already in Busan” matters
You do it on a day you are already here, instead of treating the lesson as a reason to change cities. The studio is in Haeundae. If the day is already a beach day, a Dongbaek day, or a night out, the lesson is a stop on that day: about an hour, or about 40 minutes for eyes and brows.
What you are not being asked to give up
You are not being asked to skip the rest of Korea, or to pretend Busan replaces it. The answer says the trip stays on you after you leave because of the skill. The other cities remain whatever you planned. This hour is the part that is still in your hands at home.