People really enjoy complaining, when literally the point of the drug scene and what happens because of that, is being something you DONT want to read, and that's the result the scene causes.
This isn't NTR, nor it's a fetish, the focus of the story i dont think it's to be a "dark" fantasy, or to be something like that, imagine getting upset because the 2d girl you wanted to be your waifu isn't the virgin pure anymore, it's a resource for the story, for the developing of a character, you aren't supposed to enjoy it.
The author has another ln, and another manga, in wich he talks about trauma, about feeling numb because of it, it shares apathy, and the feeling of being emotionally blocked, being unable to reciprocate or to feel anything, be it bad or good emotions even when he understands that the people that hurted him before always loved the mc.
So far this one is looking like it's mostly about anger and escaping, it doesn't feel like a satisfying revenge or reward, it's just coping with the feeling of being betrayed. It doesn't matter the circumstances of the betraying, probably he will still feel betrayed always anyway, the reason for betraying doesn't matter, the author doesn't treat misunderstandings as something you clear up and then everyone feels good and alright.
If you cant enjoy a story like this with the focus being the feelings and the development of the character, it's totally normal, you can go read like 50 mangas about the hero being betrayed, without cheating droging or anything else, chapter 1 they kick out the mc, chapter 2 they realize they cant do anything without the mc, chapter 3 the revenge, chapter 4 onwards nothing because that's the whole kick of the series, there are like 10 new stories like that posted everyday.