These self destructive activities us the biggest vulnerability to his career, and he's showing MC it straight off the bat. To test the strength of their relationship and trust.
Bro he's choosing to do all of this willingly, according to what we know so far ..he's a successful model who was just chosen to a brand ambassador and him getting with haeyool which obviously has feelings for yeongwoon to just use him to mess with his ancle and now dragging the mc in this mess..where does the cry for help fit in in all of this (⊙…⊙ ) the only excuse there is for him is his brother or stepbrother's death
The author decided to show this scene for a reason. Seo in is testing boundaries and provoking. MC might be the only person that knows/truly cares and would reach out to help. If I saw my friend in that situation it would be a cry for help. Seo In is clearly dissatisfied with his current life, and MC might be a bacon of hope. Someone to help snap him out of it. It's easy to declare a character as "bad or evil" but there's much more nuance in real life. Think about how Seoin spiraled to this point and what he's truly showing.