It's about ethnics. Dan won't just be betraying JJK he would be betraying the manager who had been kind to him, potato and whole of team black. Also that drug being said by Baek Jumin's manager is so shady. If he accepts that deal even from a practical point of view he might find himself in a worse off position.
Ok since everyone and their dogs know about JJK's toxicity so it's not new news but why the hell even after 48 chapters we don't get a single morsel of Dan or JJK's backstory? Heck I have so many questions about Dan. Is his grandma his only blood relative ? What happened to his parents? What got them into that debt ? Anything ? They could atleast add some interesting snippets about the character's peculiarities or some hints ?
It seemed like a sec that the seme was going to have a cardiac arrest from MC's antics