The MC is so weird. On one hand, he caused the death of his two orphan friends, ordered the murder of the dad of one of his childhood friends, but on the other hand didn‘t immediately dispose of the Vice-chairman and didn‘t kill director Ham either. Pretty inconsistent.
What‘s consistent tho, is that he‘s a giant asshole. Always has been, I guess.
Let‘s see what the epilogue brings.
Btw is chapter 70 really the last? Title page says that no. 71 is the last.
Because manga aggregators, including Mangadex, don't have special tags for Afterwords, we end up having to number them as chapters, but the last chapter for this series is really 70; 71 is just the author commenting on this project.
And Sangwoo is indeed an arsehole. What makes this series interesting is that he's dealing with even worse people. In the case of Dr Son, I have more of an objection to his forcing Suhyeon to do it than the killing itself. Sangwoo said in no uncertain terms that his own life was at risk if Dr Son perfected TCM. And he had reason to believe that, given his previous interactions with Jisang. But Dr Son just went ahead nonetheless, so I can kinda understand that Sangwoo was acting out of self-preservation, which is more than I can say of Chairman Ji and Woonghoo. The murder isn't justified, but at least it makes sense that between Yuna's Dad and himself, Sangwoo chose the latter option.
I think in the case of the Vice-Chairman, there was no inconsistency. He was asserting his dominance by making Suhyeon his minion. Nor was there any inconsistency in the case of Director Ham: Sangwoo is actually less petty and more open to less violent courses of action than Chairman Ji, who killed Sangwoo's friend out of pettiness. Sangwoo can see Director Ham has been rather dependable (he only won against Woonghoo because Director Ham agreed to change sides), and is the only person who can conceivably keep overseeing TCM production without trying to stab him in the back.
There's also the issue that Sangwoo has retained a small bit of humanity. We see him consistently trying to find people he can have some sort of relationship with, like the idol and even Suhyeon.