Interesting! After I saw your comment, if we connect all the things about Seungmin was raised in Brazil and how he somehow become like secret detective through this drug business, I also think somehow he was responsible about that drug reproduction or the distribution. I feel like he felt guilty because he couldn't stop that and then it hurt an innocent person.
I also have this theory that it’s possible Seung Min became the drug mule in exchange for a chance at a better life in Korea. The theory seems inline with the guilt he’s feeling as you mentioned. Can’t wait to dig deeper. (▰˘◡˘▰)
I previously mentioned that, theoretically, it was possible Jae Young was drugged at the Favela club, with Seung Min supposedly being the club owner.
However, I take that back. Now that it has been revealed the drugging took place somewhere Baek Jun used to frequent, it likely could not have been Favela. This is because Baek Cheolmin mentioned that they were only planning to officially distribute the drug in Korea, with the Favela club intended to be the first location in chapter 16.
So when Seung Min said Jae Young got hurt because of him, I don’t think it’s just about the club incident anymore. It feels like there’s an even bigger and more shocking reveal coming. Maybe it goes all the way back to when Seung Min was still living in Brazil, or maybe my theory about someone in Seung Min’s family being involved in the drug business or production might actually be true.