Why are there very few underdog kdramas like Itaewon Class?

I love this theme and have been looking for more shows with the same theme. Itaewon Class was perfect, from casting to storyline. I even enjoyed the main couple's storyline that was different from the usual. It was really popular when it came out despite the mixed reviews. So any idea on why the theme is so rare to find in newer shows? 

 Saygo:

I feel like they are there. They do tend to centre around bullying  and revenge mostly. I like seeing weak to strong character development too..

Ya that's what it is! It's mostly about revenge which Itaewon Class was about too actually but it was nice to see a drama about someone build something huge from nothing