[@Mr Allen J]

If I had to pick a central theme in the story, I am going to be a pessimistic and say the real theme in the story is that success is a zero-sum game. The tournament arc is a really good example of this mentality; only one person can win this tournament, and a lot of people's hopes and dreams are or were riding on this tournament. Justin needed the money to hide away but was knocked out. Meo needed the money to save his village and he was knocked out. Yeong-Suk needs a good showing at the tournament or she and her family could be facing dire consequences back home, etc.

Everyone's dreams is built upon the destruction of someone else's dream.