Or.... and I am just spitballing here.
He was just a kid with a shitty life and hated the hero who seemed like he had everything with his stupidly upright attitude.
Maybe because of his shitty life he wanted to get back at the people he thought were scum. And after he got some brains and power he got rid of anyone who got in his way. The hero, with his self righteous manifesto was the ultimate hypocrite to our villain.
I like to think that maybe hero or hero's family had something to do with Ling Chen's parents... Like a car accident or something.
Since they have never been mentioned they're either not in the picture because they've abandoned him or are dead (which I think is more likely).
I'm also spitballing here, since there wasn't a single mention of his parents, but... he seemed to have hated the hero way before aunt or the girl (before something happened to them).
... So maybe? ╮(￣▽￣)╭
There is only two people which is his aunt or the long haired girl. Could it be his aunts death was because of the hero guy? I thought in the first life she was killed by the uncle on the day his uncle was asking for money. So it can’t be.... maybe the hero dad had something to do with his family being poor and indirectly caused her death but not likely... the only thing left is the long haired child hood friend
She seems to like the MC and the three of them were friends, in the first ch the hero said he was made at her for acting suspicious, it seems like he is saying that she was cheating them but now I think it’s because she became a defense lawyer and defended bad guys and our hero has a warp sense of justice being overly obsessive
So he could have gotten mad at her at that..... maybe she was hurt or died...
What could make him hurt his friend so much it seems like their whole friendship was a fake since the beg8nning because he stated he lowered himself to become the hero friend