Plot holes: okay so how and when Heejae became rich after being left behind by his parents...

Plot holes: okay so how and when Heejae became rich after being left behind by his parents? I kinda wish Seyeong's past also has some depth.

I would also like to know the reason of the sus stare from Woohyeon towards Seyeong during the night gathering. Why did he stare like that.

I think the ending is just too rush and no side stories kinda make me feel everything was abruptly ended orz