The main lead ruined the whole movie

For the first few episodes, Nam Do-san acted like a good, innocent guy. Later on, you will see this main lead turns into the most toxic guy with many lies and manipulation. He still got everything he wanted no matter what he does is right or wrong, just because he is the main lead.

Also, it doesn’t describe the reality of a start-up life at all. So unrealistic

I really don’t understand why people can sympathize with the main lead (Nam Do-san) and think that he is a good person. He is completed not!