Responses
So far I think these reasons:
-Mincheol was popular and the best at school and couldn’t get to college.
-inferiority complex. Others could get a better life except him.
-Haesoo’s miscarriage
-Being always at the top, he needed someone being inferior at him. and Haesoo took that place.
-Probably Haesoo's father took his tuition money, because Mincheol pushed him.
-And finally, the debt and lack of money.

All i can think about is what made this man change?