But isn't Soju way too expensive in restaurants?

I understand the purchase price for Soju is in the low 1,000 won range
I remember when I worked part-time as a kid, it was 1,000 won per bottle
Most places start at 5,000 won
And if you go to busy areas in Seoul, there are many places where it's 7,000 won
The selling price seems way too high compared to the purchase price