the reason hes doing this to the bottom:

*BASED ON THE NOVEL*

so back in middle school, the top liked the bottom but the bottom was homophobic and was violent bc he was in some sort of gangs or whatever (not sure, kinda forgot) he did mention in the manhwa that all he remembers in middle school was fighting. So yeah when he found out the top liked him, he went to the extremes and had the top gang r*ped