This isn't even the premise of the story tho?
The students volunteer in these auctions so they can receive pay for their blood. Nicholas participated not only to send money to his family but he's in that school to learn stuff to help his country.
Why do ya'll always gotta make the least charitable takes?
I feel like you're not even reading the same series. It's obvious the students have this system setup so it's mutually beneficial for the humans and vampires. The humans get money among other necessities while the vampires get their main source of food ethically sourced.
Nicholas is even able to attend their school 'cause of this system. He wants to be there to learn and help out his country with what he learns.
Why are you acting like this is all non-consenual??
why do mangas keep doing the "well I'm a slave but it's ok because my master is nice"...