Yes. Cinderella plot is common, poor with rich guy.
About the debt. Once I listened a documentary about the debt crisis in Korea and a high percentage of Korean households are in debt, specially millennials and how that inspired the Squid Game. The Korean media always shows the loansharks even in old movies, so I’m not sure how common they really are because I have never lived there. By the dramas not just manhwas, looks like there are a lot.
As a crazy anecdote. Once I heard two guys knocking my door and I was wearing a goofy Christmas pijama and they had like a baseball bat and an steel tube, they asked me politely about one person whereabouts and I told them I didn’t know and they went to knock the door of my neighbour.
Why do koreans love making this kind of characters so much? Poor, in debt all their life that THEY have to pay, being chased, beaten or sexually abused by loan sharks, not being able to at least win a little in life. It's so sad whyyy